The reason we can't judge aizawa as a teacher as well as we should is beacuse we don't know what he expelled his previous class for. But judging by what behaviors he allows without expulsion ( ie bakugou and mineta) it mus have been something pretty Nasty. So I'm all for Polarmare calling him out!
That is very true, the only problem is that he has on record in canon expelled an entire class and I really doubt the scum of the earth all got into one class so I do think Aizawa has expelled students for stupid ass reasons.










