>>22145722In the narrative of the episode it's because Jimmy said "production was like you gotta chill." Sam had just said he didn't want to hear the word "producer" again but also said he'll let Jimmy do "whatever" because he can't follow rules and is interesting anyway. Therefore, they later say they have to kick Jimmy to prove that the rules do matter. It's a classic season 2 contradictory and confusing mess that is all the fault of the producers.
Personally, watching the Simon Says live it felt like a test to make sure Jimmy wouldn't blow up (even though they likely hoped he WOULD blow up). I don't think anyone ever went upstairs to retrieve Jimmy's stuff so the whole part about Sam deciding last second to keep him and go Joker mode felt phony.
