“A the-rapist” still kinda works if “the” is the title (though a little awkwardly). I’m not overly defending how it’s presented or how funny it is though so you could probably find better ways to present the joke itself. Merely trying to mention that it’s not based on sounds, so as long as you can read English, you should be able to understand the joke.

That said, it could’ve been a number of issues:

• autocorrect adding an article to an incorrect place

• general screwup of the presentation

Etc