Why would Ainge give that up for 1 season of PG13, when he could lock up Butler for three with a good contract?
Paul George is a better player (most notably a better shooter which is crucial for the Celtics offense) and that cost control for Butler is baked into the price, surely.
I have no problem giving up assets for George, I've always preferred him to Butler even given the recent contract situation. I think that after a year here of success he won't be so keen on leaving for a very underwhelming Lakers roster.