I used Unijoin multiple times this week again, and I still never had any issue with it. I guess that some amounts I mixed would have attracted some "exit scammers", and I still received my funds as usual.
Unijoin I use the mixer regularly but haven't encountered any problems yet.
I have also used it without any problems so far but someone could argue that we are biased by being paid for wearing the signature so I will try to be as unbiased as possible.
I think it was in the Ann thread that the OP talks about exit scam, but it would not be an exit scam as that means stopping the whole service and disappearing, not keeping a customer's money and keep running the business as if nothing as he says.
In support of the veracity of his version we can see that he is a person who manages quite a lot of money because of his status in the forum. On the other hand, I find it quite strange that a business that can earn a lot of money by doing things right and without cheating anyone, swindles only him for the large amount, and continues the business as if nothing happened.
In principle, and without further evidence, I am going to think that Ockam's razor does not work in this case; there are always exceptions that confirm the rule.