I am just curious, since mixers are not illegal and are at some point in grey area or call whatever you want, like Kratom and research chemicals in the USA for example, have you thought about this: Allow mixers ANN threads and discussion unless mixer gets blacklisted. For example, Sinbad.io was blacklisted since day one, news websites had published about how Sinbad was created by Blender.io team. And Sinbad got seized because it was known they were laundering money but what about other mixers? Yomix, Mixtum, (for example MixerXer) and others for example? I mean, it's okay to allow these mixers on your website but once there is an article about (for example) MixerXer was caught in money laundering or North Korea group laundered money through MixerXer, then just blacklist MixerXer and remove their thread, promotions and so on. Usually there are articles written about how money was laundered through certain mixer before it gets seized.
What is the oldest bitcoin mixer? Cryptomixer.io as far as I know (correct me if I am wrong because I am not an old user). Has there been any article about Cryptomixer.io helped money launderers or something like that? No, and they haven't been seized too.

Do as you wish of course because I am not the one who has the responsibility of managing the forum but I still think that this solution sounds fair too but maybe it's too late, can't talk any further.