I mean, this is probably just a case of TC claiming the game is rigged because he’s in denial about how bad at the game he actually is (Hey, TC do you know why the game times your runs? Because it takes for granted that you’ll win and the actual challenge is getting a good completion time. That’s how Easy this Tavern Brawl is) but it’s quite possible that Rag’s draw chance might be “rigged”.
Some PvE bosses are designed to draw X card at X turn, A.F Kay in the dungeon run and The crone in kharazan for example. Ragnaros being designed to draw his custom boss cards on certain turns, thus artificially lowering his chance to draw bombs isn’t all that unlikely.
Of course in this case it wouldn’t technically be rigging, just the Mechanics of a boss that put a certain deck at a disadvantage.