@Emanresu
I would say pure mind control is not quite right, they are being manipulated, but in a more focused manner. Hypnotized may be a closer relation. While they are similar, hypnosis is when the target is heavily susceptible to suggested inputs, where the details on how said suggestion is carried out is up to the target still. They keep their "sanity" and "reasoning" about every other thing, just now with a bias filter. Mind control is robotic. You say stab yourself, they stab themselves. No question. No hesitation. At most they may ask for clarity on a location to stab a or how deep to stab, but they will do so with out any thought into the matter aside maybe how to do it the best desired way. In other words, mind control = lifeless puppet, hypnosis = "paid" actor.
I think this because she still can reason with herself (although now with a heavy bias). This means she still understands 99% of her actions and their reasons behind them. She just has a new dominate driving force for some of them.
That being said, I do kind of feel bad for the guy as well. What he said is not wrong. This is literally one of the very few options he has. And in all honesty, it is not the worst one since he at least feels somewhat guilty for it and likely would not do so if alternate options were available. But seeing as to how they are not, at least with most of his classmates openly despising him for his skill, this is the next best thing. The drunk with power phase may come later, but currently he is just trying to survive. Thrown into a situation against his will, given a skill which only can be seen as an "evil" skill by a vast majority (which it is, lets not kid ourselves). Which basically means by no fault of his own, he is now a "kill at first sign of trouble, or just simply to prevent potential future trouble" threat. More or less his skill could literally be called a death sentence, which he now has to deal with for the rest of his life (presumably).
So while I do feel bad for the "familiar-ized" girls, I can understand and sympathize with our MC's struggle as well.