I recently answered a question (https://math.stackexchange.com/a/2688726/124095). After posting my answer and responding to a question from the OP in the comments, I noticed that the OP's avatar was a notorious cartoon frog that has been co-opted in the past two years by neo-Nazis and other white supremacist groups. As the child of a Holocaust survivor, this upset me (to put it mildly), and I called the OP out for it. He responded politely, but (I think) disingenuously, and has since changed his avatar to something less offensive.
I'm wondering whether I was out of line. Obviously this site is not meant to be a place to discuss politics, current events, and memes. But if someone used an openly offensive avatar (say, a swastika or a KKK hood) I think that would be some kind of violation of community norms, right?
I don't want to start a fight here but I really would like feedback on whether my comments were appropriate.