Disagreeing as well as asking for sources because I've truly never encountered anything about people being anti-circumcision that's felt anything beyond "that's a messed up thing to do to a baby".
Totally on board with the things you've said against mras, with the added note that they also make it harder for people to actually discuss real issues that do effect men in a way that isn't immediately assumed to be an angry wounded machismo thing. Patriarchy hurts men too, and men have some social issues that it can be helpful for them to seek support on, and the work of shitty mra groups framing that as so closely associated with antifeminism or misogyny actively hurts men by creating an association that caring about or having male specific issues makes someone a misogynistic ass by default.
Reasonable people are feminists, and don't get hung up on the origin of the word.
I purely mean I have literally never heard anyone blame feminism or any feminist group for circumcision. I think the closest I've heard is people arguing against individuals who're saying female circumcision is worse, and therefore we shouldn't dilute the conversation by bringing male circumcision up.