I can also assume that Malwarebytes may well have complained to theymos about selling their license keys on our forum. Selling their license keys is prohibited by the Malwarebytes Software License Agreement. Therefore, it's quite possible that theymos itself banned those who were selling keys and deleted their threads 
Does this mean that everyone who sells licenses for various AV and other software should also be permanently banned (and there are dozens of them), or maybe the forum will allow them to continue selling until one of those companies officially complains to the forum? I think that the rules for Digital goods might need updates to prevent future misunderstandings (perma-bans).
It's a good question, just addressed to the wrong person. I, unfortunately, do not have the authority to answer your question. In this case, the question should be posed to theymos. Only he can answer you. If you want to hear my opinion, I think that if the license keys were obtained legally, then why not.