Note if he can do this, through some HTML injection or other tricks, then your first order of activity should be fixing the system loophole that allows him to do that. If he's able to change the appearance of his profile, it's more than likely that he, or someone else, can inject malicious HTML into your page, and e.g. steal users' passwords. It's a serious security vulnerability and it should be addressed first.
...once that happens, the problem will resolve itself, by breaking the functionality that allowed him that in the first place.
It's one thing for a user to pretend/act like a moderator, which should be simply against the site rules and dealt like any normal violation. It's another if they can genuinely change their post/profile appearance in ways that allow them to appear as one. It's a relatively harmless use of a very serious vulnerability, and dealing with Henry, and not with the bug will come to bite your back sooner or later (...even with disgruntled Henry returning with more malicious variant of the hack...)