But it's the exact opposite. Being offended has nothing to do with sexism. Sexism is an objective situation of an unequal distribution of power. Sexism would exist even if everyone in the world thought it was great, and no one was ever offended in the slightest.
> but isn't the ability to recontextualize any bad behavior as sexist just because of the participants involved a huge source of power in of itself?
I don't know what "bad" behavior is. I do know what sexist behavior is: behavior the creates or perpetuates an unequal distribution of power. There is no "recontextualization" involved; sexism would exist or not regardless of how it's contextualized; like gravity. The only ethical question is whether you believe that this imbalance of power needs to be rectified.
But do people who fight sexism have power? Sure, they have some, but clearly, the imbalance of power between men and women is so large, that there is still no question about which side has more power.