Unfortunately, we do not know the terms of the contract between Hhampuz and BestMixer to arrive at a conclusive determination. I don't believe that Hhampuz should reveal the contract just to satisfy anyone's suspicions. Also, if you look at the last transaction where he paid the signature campaign participants, it lacks a bigger output of ~ .077 BTC that the earlier transactions have. For all we know, the ~.50 BTC covers the pay HHampuz is entitled to under his contract.