I don't think the forum should allow mixers until there is some form of policy on how these mixers work. We need decentralized solutions, not centralized ones, if the forum wants to succeed with mixers and if users are to be safe. Bitcoin has evolved a lot since the ban, creating decentralized mixers can work, so I would hope that the community rally together to build a decentralized framework in comparison to relying on anonymous individuals who abuse the forum and its people.
If we're waiting for the policy, it will high likely illegal because most people see mixer is bad instead of good. The government might make it legal, but the mixer will act like a honeypot because they're working with the government.
The decentralized solutions to increase privacy in Bitcoin is called CoinJoin and the forum still allow that, although it's not really effective to hide your trace compared to mixer.