When I was testing a lot with the auto-play-option I made a change to the Move-order algorithm so that the move-order is primarily determined by the amount of tiles a unit can reach.
This was necessary to make it possible the units properly exit the Skyranger and will also help aliens trying to leave the UFO to move in an appropriate order.
The prior algorithm was simply using the average distance to enemy-units. Ideal would be using the path-finding-distance as that would resolve both issues. But doing that just to determine move-order made it slow down quite a bit.
The current algorithm does, however, have the pitfall that guaranteeing something like the "executor" acting last doesn't work. But that was exactly the intention of using distances for the move-order.
I think I need to come up with a way to determine that if the remaining TUs at the furthest reachable tile is < move-cost, then we are not blocked by anything and thus should use enemy-distances again. This should make sure that our "executor" hasn't moved before the door-opener.
Anyways, this is more of a general idea for improvement based on your suggestion. It doesn't resolve the main problem of the idea, which is making sure to get the door-opener close enough to the door without being killed. 2 sacrificial pawns do not guarantee that the player can't kill those pawns and the one who would open the door. Sure, the more tanky the aliens are, the more viable that idea would become but the way the currently act doesn't have any real disadvantages other than taking longer.
But still, improving the move-order-algorithm would certainly be very helpful anyways. And if aliens spawn close enough to the Triton and the player fails to kill them, they should try to execute this kind of idea and the correct move-order is important for that.
The other problem is: I've now done 3 or 4 attempts at TFTD with version 3.5 and it already is incredibly hard. In my last and longest playthrough I made it to May 1st. I've won 2 out of 10 missions. Both of them against the smallest kind of craft. But then again I wouldn't have to play on Superhuman and considerations like that shouldn't be in the way of the betterment of the AI.