I've read your post but didn't see the section where they're saying they're using zkSNACKs for coinjoins so has it been confirmed? I understand what you're saying about them providing the service off zkSNACKs back for premiums in fees & privacy being decreased but how do you know UniJoin's using zkSNACKs.
Multiple users have tested it, their deposits and withdrawals included coins from coinjoin rounds zkSNACKs coordinated.