Understanding っていうのも

Question

The kids have decided that they don't like their new teacher:

A.「ああいうタイプは気取ってやがるに決まってるんだ」
It's certain that this kind of person acts like a snob
B.「決まってるっていうのも強引だけどたいていそうだよね」
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.

Answer 1

That の is a plain nominalizer, and って is a colloquial variant of the quotative particle と. 決まっているって言うの refers to the action of saying 決まっている. 強引 is a na-adjective here.

Saying 決まっている (=definitely) is too assertive / too much, but it's usually like you say.