The fanatical Muslims who would carry out such an attack are not concerned with such things.
If ordered to, you’d be right. However, they have been able to carry out their attacks without anyone and everyone getting really worked up about it. A deliberate attack on a school would change that.
Key to this, IMO, is the fact that they haven’t already done so. It’s not that they haven’t thought of it or aren’t capable of it/ I think that it’s because they know the consequences of doing it.