Yes, that is just fine. Not particularly imaginative, and I wouldn't use it, but users are entirely free to select any username they want. Unless they go for something particularly offensive, in which rare case that might be changed.
Should you ever happen upon something like that, flag one of their posts for moderator attention using the "other" option, and explain you have a problem with the username. However, in this particular case there is no need.
Moderators of the site however, will stand out by the ♦ character next to their username. And should that still not be clear enough, then you can find a list of moderators on every site. Go to the Users page and select the moderators tab. For Meta Stack Overflow it's this page for example: https://meta.stackoverflow.com/users?tab=moderators