How surprising, more assumptions. You do not know anything about the agreement between BestMixer an Hhampuz. Anything you say is based on nothing but your hatred towards anyone on your shitlist.
I suspect that if HHampuz had just left the BTC untouched, in UTXO that Hhampuz has full control over, QS would have opened a similar thread raising suspicion on why Hhampuz was keeping funds in UTXO that he had full control over. Also, if Hhampuz moved the funds to any other address, QS would find some narrative to paint him in a bad light. And if Hhampuz came up with any plausible explanation, QS would construe that too, to fit his narrative.