How does one flag potentially offensive usernames like "Anti-American Anti-Zionist".
And more importantly, should we be allowing such usernames in our community?
As sempaiscuba said, the words themselves are kind of a marginal case on offensiveness. If I were to try to make a hard rule, I'd say the first half is out of bounds since its referring to a nationality, while the second isn't since its referring to political opinion. However, if I take into account the history of the words, the first half tends to be used in some rather benign circumstances, while the second has historically been used as a label to both promote and justify mass murder. So no matter which way I look at it, half of it is probably offensive. I can chose to interpret the whole thing as benign, but I have to do some mental gymnastics to do so. (I'm inclined to think this may have been by design)
I went and discussed this in the moderator chatroom, and was pointed to this post as the canonical source for dealing with offensive user names.
I believe that if you're asking and answering questions or leaving comments around with your name attached to it, then it is better (and I would go far as to say make it a policy) to not have any objectionable/vulgar content as your display name.
There is a place for reasonably vulgar words used in a non-offensive, targetless manner. That's in your profile in the "About me" section.
The executive summary is that user names are special, as they are plastered over every post the user makes, and other users are forced to type those words to interact with your posts. For that reason, if anyone plausibly finds a username offensive, it should probably be flagged and reset. We are trying to be a welcoming community, and people should not be forced to type things that they consider slurs to participate.
If the user wants to baldly state that they are anti-Zionist and anti-American in their profile that's OK. If they want to put those exact words in a post, its debatable. But if someone flags that as offensive in a username, I'd feel compelled to reset the name.
This has been asked and seems to have been addressed in this question on Meta:SE.
Personally, in this specific case, I'm not sure that the username is actually offensive. For all we know, it may simply be an accurate description of that user's views. In any case, it does give some advance warning of potential bias that might appear in questions or answers from that user, and perhaps might also highlight that we should be aware of the possibility of 'push questions' from that account.
If questions or answers posted by that user (or any other user for that matter) violate the SE Code of Conduct, simply flag them for moderator attention.