Livre d'Or

Oh, so that's where the story of the Hellenized Jews building a gymnasium and de-circumcising themselves comes from, I'd heard of it but didn't know that was the origin. I still think you have way too much faith in Josephus as a historian. This is classic history-written-by-the-victors; the Hasmoneans won, so they distributed propaganda to the effect that the other side were awful terrible people who wanted to do away with Judaism and were loyal to the famously evil Antiochus. Josephus accepted a lot of this stuff really uncritically, plus he was writing with his own slant to curry favour with the Romans, as you have observed.

I think it's likely that some people wanted to reject Judaism altogether and become full Greek citizens. There's always some people like that in any integrated society. It's also the case that the originators of rabbinic Judaism were really brilliant (one might say, inspired) in how they tied all their innovations to a system which had a visible origin in Torah and Judaism as it had been before they came along and completely restructured it. At the time of the Hasmoneans, the proto-rabbinic faction were just one more group who wanted to change things and move with the times. Lighting shabbat candles and supporting business using interest-bearing loans and deciding things by a majority vote of rabbis even when it goes against God's direct command in a heavenly voice, and all sorts of things seem normal to us because that did in fact become the dominant strand of Judaism, but when they were first introduced they were probably as shocking as building gymnasiums and trying to make yourself look uncircumcised.

I think it's also likely that some of the Zealots accepted some of these innovations but not others, such as the decision to fight in self-defence on shabbat in order to preserve life. Some of them were probably unpleasant no-compromise-ever fundamentalists, others were probably subtle and thoughtful and trying to hold the balance between tradition and modernity in a different place from the Hellenized faction.