I'm not on Facebook. Is it possible for me to view a person's post on FB without joining? (IANAL) If so, I don't see how it could be a violation of privacy, since there IS no privacy to be violated.
However, as a matter of courtesy I would accede to the individual's request. Though that request might have been more courteous.
Always glad to hear that a friend avoids Facebook like I do.
I don't need their brand of tracking and monetization.
That said, I have read a few FB posts with tracking/cookie shields up.