It takes more than 15 minutes to get from the Sulaco to the ground. That's one way of a two-way trip that also includes a detour to a derelict ship. Even assuming he had found the Jordan's log detailing where in the derelict they found the eggs, he still needs to fly out there, set down, get out, grab an egg, and stop it from impregnating Hicks on the way back up to the Sulaco.