Your first guess (1.) is right. The clearest way to paraphrase the caption is probably:
I am not a feminist: because if I were a feminist, I wouldn't tolerate you people.
2) Is good grammatical English, but it misses out the clear assertion in the original that, 'I am not a feminist'.
3) Is also clear, common and acceptable in colloquial speech. It wouldn't be appropriate in every register, though, because it's ambiguous between: 'EITHER I'm not a feminist OR I wouldn't tolerate you people' (logical disjunction: which is semantically strange here, but grammatically OK); and 'I'm not a feminist, OTHERWISE I wouldn't...' (subjunctive).
As to whether the original is 'good English'? NO. The 'or' in the original sentence can be seen as a synonym for 'or else' or 'otherwise'. Because the word or is so common and has so many uses, this usage can be confusing. So, if 'good English' implies stylish, educated, logically clear, unambiguous... the original caption is a fail.
i) In a film caption/subtitle, terseness can trump style. So the original might have been a great choice of words in situ.
ii) I always try to give references for my answers, but I don't know where to begin on this one... suggestions, anyone?