Okay it's easy to Monday Morning Quarterback this (

) and say to pull the squad out at the first sign of weirdness or the fact they couldn't have any explosive weapons fire/grenades.
However had Gorman done that, most likely the squad would think of him as being weak or even cowardly. Marines don't high tail it at the first sign of trouble- they improvise.
Gorman is fresh out of the USCM equivalent of West Point, has nearly zero field experience and is dealing with "not" the most discipline bunch of Marines. So he can't take the chance of looking anything less than "in charge" in their eyes, and so he has them press on inside the hive despite the weapons restriction.
And on top of all this, they weren't expecting an ambush by an overwhelming number of enemy warriors- they were looking for civilians, and "possibly" some Xenos that might pop out. They probably believed the Xenos had overrun the colony, so the civilians had abandoned it in favour of hiding out in the processing station. Up until the main attack I don't think anyone thought the civilians had been kidnapped.
So now they are in the hive, surrounded, and the shit has hit the fan
very quickly. Gorman continues to go "by the book" and starts relaying orders to Apone to fall back to the APC- however by then there is too much interference from the processor and communications go dead. So at least he "did" try to pull everyone out, it was just too late. Gorman's downfall was going to pieces once communications were out and his MSgt was a casualty.
What would "I" have done (considering I have even less combat experience than Gorman did

)- Despite the fact that the idea of running the squad from the comfort of the APC and not being with them is repellent to me, I more than likely would have done exactly what Gorman did up until he fell apart.
At "that" point, I would think that my only option would be to pull a Ripley and rescue the squad myself. I would just hope I could handle the corners in the APC better than her.
Kevin