May be, if we look at their attack analytically we can see them deploying the following tactics (very similar to specialized police units and similar forces):
(0. Sneak up to the enemies position as far as you can)
- Disorient and confuse:
Here they used their psi-like abilities to emit a flash-bang-like wave blinding everyone and even knocking them to the ground. - Access the room:
if possible through improvised holes in the hull of the building (if safe to do so), else through doors and windows. - Supress and terminate resistance, immobilizing the enemy (cuffs or shots): Again done using psi-powers.
At this point we see Eli has been affected by psi-powers (see 1) but he has NOT been pinned down, meaning he is either not deamed to be a threat (which Eli made the advisor immediately regret bashing him with a lead pipe old-school style), or the advisor is not capable of pinning down more than two people.
If you look at the feeble brownish ray in the air resembling hands and holding Gordon and Alyx down it may be some form of physical/spatial limitation.
Well you know the rest, arrogance seems to be one of their weaknesses btw., as the first advisor didn’t even wait for the second one, and no guards were positioned outside.