...also, thinking about it for a while:
I would seek out a second opinion.

If this was the first hypo/manic episode he has ever experienced to this degree at least, it sounds like it was induced by medication/stimulants.

In that case? It is difficult to discern whether he is actually bipolar or not. When you get down to the specifier- I, II, NOS... if the determination of BPI has been made on the occurrence of this episode? There is very little that you describe that actually would SOLIDLY put the episode into clear mania territory, as opposed to hypomania.

yeah, he was acting out of character, drinking excessively, all the things you listed.

But he wasn't CLEARLY acting so out of character that people around him noticed that something was drastically wrong until he started on the downswing [it sounds like]. That is- you don't mention psychosis, life endangering risks, hospitalization, trouble with the law.

I would seek out a second diagnosis to get some clarification on this- I'm kind of confused how he was diagnosed BPII but then BPI because of this episode if he has never before been dx'd BP.

If this was a case of substance-induced elevated mood, it seems like jumping the gun to prescribed an antipsychotic and a mood stabilizer... I had the impression from your description he wasn't even experiencing psychosis.
I'm not saying the DX is WRONG, but it's a good idea to double check