Season 3 must be ass for him to quit, I would not be surprised if we get a Dragon Ball Evolution treatment
Given all the drama of the casting especially vivi and cobra and thus political strife that directly reflects on certain extremely horrific situations IRL atm too, it just feels like too much of a massive timebomb waiting to go off ironically with the pell and crocodiles bomb storyline too lol.
Also alabasta being such a huge, complex arc and also in scale with the setting can't be helping too.
But for all we know maybe he's dropping out due to Netflix or Oda but given he's such a superfan, its extremely weird for him to give up on this and especially unlikely for Oda to be the reason too.
As you said, the most likely option is the most obvious and simplest. It's gonna be a fucking disaster lol. Dragonball Evolution, Netflix Avatar TLA or even the much worser movie of ATLA too.
Awesome pfp BTW!