Like what I said in many posts in this topic. zkSNACKS' decision to filter transactions was truly never for the benefit of its users. It was made for the benefit of its own protection from government harrasment.
You said "An ordinary user would be digging himself into a bigger hole if he mixes his coins with what usually would be the criminals' coins." zkSNACKs obliged your concern and is refusing to do business with criminals on your behalf:
Something to think about.
It might be safer to leave them alone. Tumbling with Coinjoin and mixers might mix your coins with the coins of criminals, black hat hackers, and dark market drug dealers.
But think about it, tumblers and coinjoins are not cheap, and who would be willing to pay for them to keep their privacy?
I believe an ordinary user would be digging himself into a bigger hole if he mixes his coins with what usually would be the criminals' coins.