I don't think you should have been flagged for such an observation in general, but assigning a prior of equal probability strikes me as frankly absurd. It would be much harder for someone on the same ideological "side" to have a motivation to murder. False flags really aren't that common, in general. This is the same kind of conspiratorial thinking behind Alex Jones' "crisis actors".
Also, your comment was off-topic to the sub-thread. People were discussing whether Kirk would be seen as a martyr. The ideology of the shooter has quite little to do with that.
> (I'll probably get downvoted again for this lol)
Commentary like this is inherently obnoxious, and tends towards self-fulfilling prophecy.