No one can force them to stay. They're already obscenely rich. Think about what their motivations must be.
Either way it's not a pump and dump, and their goal is to turn the company around.
They're alpha dogs in the absolute worst sense of the word. They thrive off ego, winning, power, greed, narcissism and all those other lovely traits most people pulling similar moves seem to have.
Think Gordon Geko. Remove the pin stripe suit, fast forward 30 years and change the modus operandi from cynical asset stripping to cynical stock hyping and you get...
Edit: a more charitable view, in Pincus' case, is he isn't THAT evil and instead simply made a hugely expensive mistake buying OMGPOP. That wrecked the balance sheet and he's holding in there trying to recover.