For a start, telling someone flat-out that they're wrong probably isn't going to get you anywhere. You're starting out putting them on the defensive, which could be a barrier to further communication.

Next, there are aspects of characterization that are up for debate, especially in a game like this one where mind control is a major part of the premise. It would be better to ask the mun's reasoning and then engage them at that level, so the both of you can make sure there's something you haven't missed.

Finally, the last part of your crit was what we felt was sarcastic and belittling. Phrasing it as you did implied heavily that they know little of their character while you know everything. We're not saying you can't disagree with one another, but that disagreement shouldn't be accompanied by denigrating someone else.