In terms of the tiles falling, the AI part which controls that surely has but one single initial aim - make it so the board can be moved with a match 3. The two operations which disrupt that are when cascades happen or when the board is reshuffled because no match 3 is possible. So that is all that part of the AI is doing and as soon as it finds a state it no longer needs to do anything then it stops but not until the board resolves. Don’t forget that after match cascades also happen on a players turn - I have killed the enemy team and had to wait for a good 10 seconds or so where the board is still resolving my cascade before I get the win banner. Probably what is happening is that the AI isn’t checking for win conditions until after it has found a stable board for whomever turn it is, so it allows the cascade, that finishes and then it looks to who can fire a power or move the board, determines there is nobody and ends the match. The player is locked out from retreating because the AI hasn’t finished trying to establish it’s primary task and isn’t ready to hand over turns.
As I understand it the game creates a huge pillar of random tiles when a match starts and not each tile when it drops. So the tiles are already determined, we just can’t see them (sometimes I think the AI can, though). When I try to cheese a quest objective in DDQ wave node and want to quit a match I can’t when a cascade is active on my turn that finally will down the last opponent.