Facebook is a platform capable of controlling large numbers of people through subtle manipulation with techniques and at scale not previously possible. There have been instances where it seems that capability is being tested (whether by Facebook itself or groups leveraging its platform). It's imperative people research this legally and ethically, which is what is was being done by the NYU group.
The ethical complaint is that they accessed data without consent:
> "Facebook defended the action Wednesday, saying: "We repeatedly explained our privacy concerns to NYU, but their researchers ultimately chose not to address them and instead resumed scraping people's data and ads from our platform," a spokesman said."
My read is they are talking about an advertisers right to privacy of the ad. This is simply not a thing. The advertisement is unsolicited communication, and belongs to the user receiving it. Otherwise it sounded like they were collecting no user data other than indirectly based on the metadata used by the advertiser to target the user that already agreed to it.
