[Zipuli]

I think it simulates a situation where the mounted infantry/vehicle spot the danger in the last seconds, manage to dismount and doing so manages to prevent the AT-weapons from hitting the vehicle, but the infantry is mauled dismounting...?

In reality it could go as follows:
-vehicle with infantry mounted, yet unbuttoned (commander/troops with open hatches) spots the enemy trying to make the shot (the AT-man may have to move to get clear shot and doing so is spotted)
-mounted infantry opens fire from the open hatches, not hitting anything, but pinning down(/forcing to take cover) the guy(s) with the AT-weapon(s)
-vehicle stops and dismounts
-the rest of the ambushing squad open fire with small arms and nail the dismounting infantry inside/barely outside the vehicle
(-the vehicle manages to withdraw to safety or is left in the open to receive the next shot)

It's normal that the mounted infantry rides with open hatches/vehicle commander is unbuttoned, and most IFVs/APCs have the ability for the squad fire from withing the vehicle even if there are no troop hatches. Even if the infantry in the vehicle doesn't see the enemy, if commander commands "fire left side, disembark!" the blind firing may cause the enemy to take cover briefly.

Zip