So are you suggesting that Bishop's behavioral programming could be easily overruled by a sinster SO-937 type order that was already installed?
Most likely impossible in-universe, and makes no sense as Bishop had plenty of opportunities to acquire a specimen. He would've taken advantage of Burke and all of his antics, too.
I've been thinking that the placement of the egg, as well as the time the queen spent on the Sulaco, are meant to suggest that she 'stuck' the egg somewhere under the floor grates while pursuing Newt. It could've been a different section that was just off camera in the film.
Hell, she could've stuck it down there to get at Newt specifically. The placement fits with the queen reaching down and sticking it to the beam.