Hollywood Cannon
I'm Away From My Desk
But the armour doesn't cover his entire body. The clothes underneath were wet but undamaged. It's a poor plot device, if you're correct. In non-canon book lore, Boba Fett blew up the sarlacc from the inside and survived; I imagine they'd go down that path here, too, if Boba Fett is still alive.
The armor played a key role in those situations though allowing him to get out. Nothing is going to be perfect here though. I can look passed the non armor clothing if they go that direction. There’s been far bigger plot holes in this universe.