That was YOUR OPINION about people's behavior in venerable state. As Ap0crypha has pointed out in that moment, the Inquisitor is emotionally devastated, and not thinking rationally. She just wants to let it out to anyone at this point. Of course, it may not be the best idea to let it out to someone who already disdain of the Dalish's heritage, but if you're saying it's the Inquisitor's fault for not having enough sense to talk to people who's more forgiving then you're being ridiculous.
How is this even justify Sera's action and make Sera's response to the Inquisitor's faultless.
...and? Since Day 1 of Sera's involvement with the Inquisition, she has, when spoken to about it, made her opinion of the whole ordeal abundantly clear, to anyone that would listen. Banter between here and Solas should make that even more clear. My question is, since these people are supposed to be rational the rest of the time, why was Sera still there? She can be kicked out of the party in every conversation you can have with her, and yet, these people that don't like her kept her around, and then, in their "emotional distress", ran straight to the only person likely to throw it in their faces, and then they're mad because, surprise, she did? Tell me, did they tattoo their significant other's name on their neck too? I'd say it's ridiculous to expect sympathy from someone that's been deriding the whole culture for the entirety of the game. Expecting people to act according to how they've been acting isn't ridiculous, it's realistic, or, more accurately, being a realist. Sorry she rained on your pity party, but really, she's been raining on it since she joined up.