Using multiple accounts isn't cheating. I get that you believe it's unfair since the method he used isn't very commonly known, but it's nowhere near dishonest when he's solely operating those accounts. If he was using a program to do the dirty work for him I could see that as breaking grounds for punishment, but he hasn't broken any rules. The only rule that concerns multiple accounts would be for having alternate accounts idle in your house/guild house as you farm (I think)

Either way you're still gonna reply because you believe you're right no matter the situation.