Social Network Analysis research gets icky.
I have to admit that I see how this happened, and I would probably have signed off on the ethics of it myself (or been willing to be part of this). But I can see how it looks pretty bad to be caught doing it. And frankly, maybe it is pretty bad.
OTOH : I think what they found out knowledge worth having. But it's largely worth having in order to know the danger that corporations having this power present. You wouldn't want the academic study of this to be banned, and for the research to disappear into internal surreptitious tinkerings where no-one else ever sees the results except in private reports to the marketing department and advertisers.