It's never been a multiboxer versus non-multiboxer policy, it's simply a "is this player following the rules" policy. Harassment and foul/offensive language is clearly against the policy of the game, and therefore something you can report someone for.

Also, please refrain from click-bait thread titles on this forum, where the title is not treated as the subject matter of the thread, but is instead used as an opening part of the initial sentence to draw someone in, act as a standalone "cliffhanger," or both. I've edited the title and initial post for clarity.