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.
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."