If you trigger the gas and fire trap in the Dank Crypt sarcophagus area, the flaming bolts will continue to fire until you press the right button or get the hell out of the trap area. You don't go into turn-based mode. So the Guardian trap isn't even the only one in Act 1 that works this way.
Just think of traps as an environmental hazard like surface effects. It's not an "enemy," so it doesn't automatically throw you into turn-based combat mode.
I believe it does go into turn base mode now. As it should.
The point is that something shouldn't act outside of turns *while* the player is in turn based mode. The player, in that instance, is out of actions while something else has an infinite amount of actions in said turn.
It's clearly a mistake/oversight that has to do with early access.