Seems to me that it's going to be a bad day for Sinbad.io
Are you suggesting mixers to start hiring government agencies to approve the coins coming in to them then mix the coins of their clients?
Obviously not. They're just saying this will lead to greater scrutiny for them which could eventually lead to their shutdown, ala ChipMixer.
Just because a random Blockchain analysis company claims something is gray does not mean it is gray. Blockchain is open for everyone to trace transactions. Why don't they show the transaction reports, the connections, destination addresses everything publicly? They will not do such thing because they may not have concrete conclusion.
The difference between them and a random person commenting on this forum is the claims they make are backed by enough evidence to hold up in court. They can withstand scrutiny from an analysis team hired by a defense attorney trying their hardest to poke holes in their findings.
How did they even know it ended to address/es that is/are from Sinbad wallet?
I would imagine by sending BTC there and tracing where its going. Also there could be instances when BTC was known to have come from Sinbad and they trace it back to its origins.
Remember that just because a mixer claims to have certain procedures or security measures in place, it
doesn't mean they actually do.