[Tinos]

Oh boy this sounds like quite the situation. You obviously understand the internal affairs far greater than I, but you did say "I am the person who has to put him in his place". Not saying this is the solution but if you're the person who put him in, you're probably the best person to kick him out?

Again, I don't want to meddle with decisions involving total stangers' careers but philosophy that the CEO at my old company had (which was a startup optimising for 100x efficiency) was "hire fast; fire fast" and his startup is doing pretty well under that mantra!