Well isn't that a tad awkward

If I'm not mistaken, once you sign up to Facebook, whatever you post becomes their property. I don't know if FB sells the photos, but there's something about ads, cookies, etc that can allow third-parties access to your posts.

no. it does not become facebook proberty if you upload some picture (thats just a myth some people who don't read the agb are spreading). you have the rights for your images, even if you post it. facebook have just the rights to use it on their own website, but not for selling it to some weird nsfw websites or other locations on the internet who is not part of facebook.

But others can. Doesn't instagram?

Quite likely he got a virus (probably from a porn site) that hacked his camera