1) irrelevent, he still released Corypheus
2) He was in an abandoned shack backed up by 3 other people, he has murdered numerous times before,. There was no witnesses to be had. She clearly stated her intentions
3) And he was there in the first place because? reasons? To get rich off some diamond? sounds pretty stupid to me
4) He didn't lift a finger to act against her for 3 freaking years, I'm not advocating A public execution but he could have done something. Instead he just sat in his mansion staring into a fireplace
5) Anders was advocating some pretty serious action the entire time up until that moment, everyone has to choose a side and "If you support freedom for all mages help me plant this in the chantry" If Hawke didn't suspect anything its for 1 simple reason: He's an idiot
6) So the women who has been lying to him the whole time says and what he should just take that at face value and do nothing to verify it? And your letting your morality cloud you on this one. Most people chose not to follow her anyway and had Hawke speak against her and yet he just threatens her for the list then stands there like an idiot. That you chose otherwise is irrelevent
But sure if its easier for you to be an absolute apologist and embrace hawkes evident stupidity then have at it.
I don't see the logical connection between my points and blaming Varric.
1. The security system containing Corypheus is already failing anyway, which as only gotten worse with the Grey Warden's having abandoned the place and no longer being around to maintain it. The Grey Wardens who built it knew that he was too powerful to contain and it was only a stop-gap measure until they could figure a means to properly deal with him, but they never found a solution, hence why they were forced to hire mages like Malcolm every once and a while to "top up" the blood seals. Furthermore, Janeka was already planning to break Corypehus out anyway, so what exactly was Hawke supposed to do? Say it's not their problem, leave and just let Corypheus ecape at some point down the road, or release him and attempt to gank the monster once and for all? He'd have gotten out either way, Hawke did the sensible thing and attempt to kill him while he was still weakened from his millennia in stasis.
2. Regardless of being in alone in a shack, Hawke's trying to keep a low-profile and keep either themselves or their sister out of the Gallows. Murdering a Chantry and a Templar is going to attract a lot of attention, especially when that murder happens just across the road from where you live.
3. So a hunt, a party and a heist doesn't sound like something that's right up Hawke's alley? We've seen Hawke (and the Warden) take far stranger missions in these games for far lesser reasons? Go to a party and try to help an assassin rob a stuffy Orlesian without getting caught? Sounds like fun!
4. Even as Champion, Hawke's title is pretty much an honourific and while that grants them certain fame and prestige, that's pretty much it. Even as the Champion, Hawke's not the most important noble in the city either, since otherwise it'd be a no-brainer who the nobles would want to elect as the new Viscount. Nor are they are Templar and have any say in the running of the Order. Exactly what are they supposed to do, when even the freaking Grand Cleric isn't stopping Meredith and she (technically) does have authority over her? We know that Hawke was doing a lot of things to help the city during the time-skips, so it's unfair to say they spent "3 years sitting looking at a fire".
5. Again, Anders has been blowing a lot of hot steam for over 6 years at this point. No-one is listening to it anymore or paying attention to him, they've just learned to drown it out. If I thought Anders wanted to put something in the chantry that contains a ton of manure from the sewers, I'd far more suspect him of wanting to tip it in the Chantry priests beds, pour it into their version of a baptismal font or dump it into the armour of the Templars assigned there. It's clear from Hawke's reaction that creating an uber-bomb as not something they thought he was planning and it took everyone by surprise.
6. True, but she fesses up about being a Qunari quite readily, so it's not like it comes out of the blue at the last minute. Secondly, the player's own morality aside, even Tallis doesn't want to have a ton of people who are guilty of know crime other than being related to a Qunari or Tal-Vashoth be executed. When a Qunari who's job includes killing Tal-Vashoth is willing to give some of them a free pass and you're not, it's should tell you who's the bigger villain in this situation and it's ain't her! Yeah, you can choose not to follow her and demand the papers, but at this point, Hawke's seen enough of her in action to know she's pretty skilled and it's not worth their time forcing the issue, because she's probably right that this information is better kept under wraps.
I'm not being an apoligist, I'm simply pointing out that most of your reasons for Hawke being "stupid" are based on information that we as the audience possess, but the character doesn't, so it's hardly fair to say this makes them an idiot. It's like saying that the Cailan was a moron for getting killed at Ostagar and that the Warden and Alistair were dumb for getting shot with arrows at the Tower of Ishal, because they'd not seen the cutscenes that told them that instead of charging into rescue them, Loghain instead had given the order "Screw you guys, I'm going home".
The logical connection is that Hawke would have never been in those scenarios without Varric, so one could make the argument that everything in DA2 is actually his fault. But no-one blames Varric because we know that no-one could have possibly known what would have resulted from their get-rich-quick scheme.
Hell, look at it this way and let's figure out where the actual blame for most of the game's events truly lay.
Act One: Varric's fault. For setting up Hawke on the Deep Roads expedition, thus setting events in motion.
Act Two: Isabela's fault. For stealing the Tome of Koslun, thus bringing the Qunari to Kirkwall.
Act Three: Bartrand's fault: For selling Meredith the Idol, thus driving her crazy.
Endgame: Ander's fault: For blowing up the Chantry, thus inciting the Mage Rebellion and Templar crackdown.
Legacy: Janeka's fault: For sending the Carta members to kidnap Hawke/Bethany/Carver, intending to use them to free Corpyheus.
MotA: Salit's fault: For stealing the list to sell to Duke Prosper, forcing Tallis to find someone with an invitation to the party to help her steal it back.
Hawke is a bit player in all of these events, but they're not actually the individual responsible for any of them. They're simply the reactionary figure that these events ended up happening to, rather than being the one who actually caused them to happen.