Crypto regulation is not the main problem on why mixer was banned. Mixer banned was implemented after popular mixer such as Chipmixer was seized due to the involvement on money laundering with NK hacker.
Chipmixer was heavily promoted which might involved the forum if they allow services that connected to illegal activities freely advertised here. There’s no way the decision will be reversed just because Trump is pro Bitcoin since the issue here is not Bitcoin rather the use of mixer on money laundering although mixer in general is not bad.
I understand the idea that the forum does not want to become a platform for advertising suspicious services that are engaged in scams. But banning absolutely all mixers on the basis that some of them were engaged in such illegal activities is very unfair to those services that do not do this. Some casinos also deceive their users, do not allow them to withdraw winnings and much more. But they are allowed to advertise on the forum. That is, the logic here is quite ambivalent, in my opinion.