the money launder does not make sense to me - everybody knows who mined the block and everybody knows where the fee goes...
So it is perhaps not tracked by current systems but it can be tracked.
could it be, that the actual hack is the following:
A sends money to B
fee goes to C
you can aim the fee going to C by only sharing the transaction with C and just wait till C gets the block
So far just creative way to send money from A to C - but what if B says the cover the fee (or just implemented it that way) - then B would provide a service/money to A thinking it got the amount from the fee.
I'm however not aware of a B that is sensitive to this kind of attack - but there might be a smart contract out there...