It's rough because while I agree that I don't want to see a bunch of court time wasted on video game cheating, this isn't a case about video game cheating. It's

It's rough because while I agree that I don't want to see a bunch of court time wasted on video game cheating, this isn't a case about video game cheating. It's a case about defamation, a defence to which is the accuracy of the claims (in some countries), and then yes suddenly it's a case about video game cheating. I do think that you should have legal remedies to defamation, and in most cases of defamation the two of you are unlikely to have had a prior contract that could have included an arbitration clause. (In this particular case they could potentially have but I suspect that's uncommon.)