Okay I sort of have an answer here, some of it already known, some of it slightly new to me.
June 25 article in NYT -- Basically, they shopped the film around in 2018, got a ton of offers... declined them all. Bob Iger was approached, and he's a fan (apparently has grandkids that have the show memorized, sound familiar? hahah). He flew out to NYC, made the pitch... got the rights.
Fast forward to 2020 - Disney announced the theatrical release, as pandemic started, asked if they could release on D+ (because the lack of production = lack of content = death of D+ going into the streaming wars), Seller/LMM said no. As pandemic shut B'way through 2021, came around and said yes.
Per Iger, the contract was "adjusted" due to a lack of theatrical release -- probably means a bit of a discount for Disney. Also claims that, it's not just about money, this was a bit of a prestige IP to own...reading between the lines, Disney didn't fully recoup its acquisition cost in this deal.
Good read if you're nerdy about this stuff.