This is a great idea and Scorch is entirely wrong
If you want things that don't make sense, it's driving a van into the middle of a cult safehouse, letting yourself get completely surrounded, grabbing all your weapons, stepping outside of the car, and THEN waiting for reaction fire.
I think this makes MUCH more sense than waiting a turn - which is pretty much a required action unless an enemy is looking directly into the skyranger.
Blocking the aliens from using a grenade until X turn is a concession to OXC since vanilla behavior didn't have a weighting when spawning enemies to face them towards the skyranger. In DOS it was 100% random which direction they were facing - where as here the numbers go up with difficulty.