The kids have decided that they don't like their new teacher:
It's certain that this kind of person acts like a snob
The thing you call certain is just pushiness, but it's usually like you say.
My translation doesn't quite make sense. I assume the meaning is "What you see as snobbishness, I see as pushiness". But if so, why is it not 気取ってやがるっていうのも. Does っていうのも refer to the thing described as 決まってる or to the phrase 決まってる itself? Or have I completely misunderstood?
Also what nuance does っていうのも give rather than っていうのは.