Facebook is quite out of touch with reality if they thought Waters would let them use it. Additionally they also don't understand what the song is about.
That sucks. How will they effectively advertise the new instagram feature that allows you to feel a synthetic form of being connected while trapped behind a figurative/physical wall of fear and self isolation?
Like... how would you use this song, non-ironically, for facebook? Who does this appeal to?
Maybe they just liked the tune. A lot of people don't think very deeply about what a song means anyway. I remember that the high school senior class that graduated a year before mine had Brick in the Wall as their class song. Played at their graduation while walking out and everything. I don't think any of the administration had a clue what the song was about until it became a big talking points after graduation.