Facebook ran an experiment several years ago where they injected either positive or negative posts into people’s timeline to see if they could alter their emotions similar to if they were with happy or sad people in person.
Seeing posts on Facebook is going to change your behavior on Facebook, whether Facebook studies the relationship or not. Paying attention to that effect isn't sinister.
Is it not? They had to apologise and it got them into quite a bit of heat with an ethics department... Interested to know how it's irrelevant or a mischaracterisation!