Fiona did not have a hand in Lambert trying to censor the mage conclave which is tyranny or any of the actions of the radical pro-independence mages.
I didn't say she did.
She just provided a choice to them about their options and informed them of the the current volatile political climate they are embroiled in and have no way of controlling. They chose to rebel.
You basically just described a mugging threat, you realize. If I inform that I have led you to a dark alley where a number of my associates can implicate you in a violent crime, an environment that could be aleviated if you just handed over your wallet... no one would confuse that as being a free and fair choice. They would call it what it was- entrapment and extortion.
Fiona posed a false delima after informing them of the current climate that she and like-minded associates helped create that put them in a state of insecurity in which not rebelling appeared tantemount to suicide.
And I don't know why it's such an outlandish thing to even discuss rebellion,
Well, for one thing it went well passed merely 'discussing' rebellion.
But for reals, I'm guessing you don't work for an enduring government, then.
(Also, who called that outlandish?)
should they just be censored and not even discuss the discord and discontent? Remain in ignorance and helplessness, even voicing your concerns a sin that will be suppressed with intimidation and violence?
Aside from the false delimma you pose, I'll also point out that the Templar response to multiple attempts at sedition and to organize a revolt were not remarkably violent, even if they were intimidating. (Which any compliance-enforcing agency is.)
Sorry, mages did not sign up for that oppression. Mages are given an informed choice, that's the only thing you can expect from Fiona. Trying to censor them wasn't going to make the discord go away.
What happened to the previous informed choices, then? Or, if there wasn't sufficent information, where was Fiona's information about the role of radical mage agitators?
The only choice Fiona cared about was the one that agreed with her.
Furthermore, isn't that what the Circle is suppose to be, mages banding together in a world that treats them with contempt?
Nope. The Circle was an exercise in enforcing population segregation from both directions.
If not then it's a tyrannical prison and the pro-rardical mages would have rebelled anyways.
Not necessarily, and they should have done it themselves regardless rather than working to hijack those who didn't agree with them (and, following the vote, fight and kill dissident mages who wouldn't revolt).