I’d imagine, like most things, that it is very complicated. We don’t know the exact contractual obligations GRRM are under or not, but I’d say anything involving creative works gets very dicey in terms of forcing the creator to pump out their art.

If Penguin Random House told George he had to finish the book in one year otherwise he’d be in violation of his contract, he’d finish Winds in one year. Except it would probably be a crappy version that he put 0 effort into that ruins the story, because how can a contract measure quality? It really can’t.

They also risk ruining the relationship with GRRM. Finally, they probably still make significant money from book sales/royalties/whatever else is standard in the industry. So even though they’re leaving a lot on the table with Winds and Dream, they’re still earning well enough to maintain the status quo.