If a consensus was reached by the public that NSWL does 'evil' things, it'd make logical sense to further investigate the possibility that you do evil things.

DARPA creates lots of things, but one of those things they focus on is weapon advancement and defense. They have a lot of creation under their belt (the internet, various medical advancements, surgical and prosthetic equipment and techniques, etc etc), but their public military image and priority on defense is such that the public has come to the consensus that DARPA is a spooky, evil, lab -- regardless of the good that they've done.

If the public consensus is that a group that Google deals with 'is evil', it'd make logical sense for there to be more pressure on both parties (Google and the involved party) to be as transparent with the public as possible to negate the brooding bad PR -- otherwise that 'bad' image may rub off and affect both parties.

That is, unless, the benefits of the partnership are greater than the disadvantages created by the negative PR generated by the partnership itself.. and I am personally of the opinion that that's the state Google is in now.