I can't be sure the usage of this "for." Is this interchangeable with "as"?

He's very talkative for a man who's supposed to be sleeping.

Can I change that?

This particular strucure with "for" is very idiomatic and is often used to introduce contrast (a subordinate clause indicating contrast).

Consider the following sentence

He's very optimistic for a man who's just been diagnosed with cancer.

You don't expect someone who's just been diagnosed with cancer to be optimistic just as you don't expect someone who is supposed to be sleeping to talk a lot.

Hope this helps.
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damn! You are beautiful! beautiful beautiful explanations.

I can't expect more.
could u tell me whether this sentence he is very interesting for a man who can tell a lot of jokes has any grammar mistakes ?
Grammatically it's fine, but implies that men who tell many jokes are not interesting.
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