Perhaps contacting Weyland-Yutani with an offer of his discoveries is nothing but a devious ruse by David?
If he really wishes to inflict his Xenomorph creations against the whole of Earth's humanity, perhaps he thinks the unprincipled, self-serving ways of this particular company will help him achieve getting them to planet Earth...as he knows they will do everything in their power to get hold of what he's offering to them...and expects these mere mortals to be unable to contain his creations once unleashed. In the same way he cleansed the 'unworthy' Engineers off the face of their homeworld, perhaps he plans a similar cleansing of his own equally unworthy creators.
Possibly...
(and I'm certainly looking forward to the possibilites for an 'extended' fan edit using certain deleted footage)