For anyone who played Spec Ops..

So yeah I just finished Spec Ops, but I've just got one question:

During the time when you were split from Adams and Lugo and they asked you to help flank through radio, you enter a room with filled with a bunch of mannequins and some stage lights. You proceed to kill a few normal soldiers, then a big heavy comes in.

But when you try and kill him, the lights go out/the screen turns black for a split second, and the game does this again until you kill the heavy. During many of these blackouts the heavy is sometimes replaced with a mannequin then he magically appears in a different spot. Was this part of Walker's hallucinations or was it just a trap by those few 33rd soldiers?