On second thought: this sounds a lot like the many "services" in the past that paid interest on Bitcoin deposits. Usually, that didn't end well.
Are you sure you want to be associated with those?
Do you have any example of a service that had an actual reason for offering a reward on Bitcoin deposits?
It seems to me that LoyceV was not directly aiming at the mixer that pays out "staking" profit, but generally at the hold of Bitcoins with a third service. I am personally of the same opinion that it is a very risky move, especially when it comes to the mixing service.
Mixers play on a very tiny line, and once they cross it, the authorities react quickly and we all know what happens after that. When you add to that the ever-present risk (hack, theft, scam...) for all online money keepers, this idea does not look encouraging.
Chipmixer had a more than good reputation, they could implement this kind of idea safely. Imagine how it would all look today.