Sounds a bit wanky, but I try and keep the harm principal in mind - if my actions are not causing myself or anyone else harm then I don’t see why there should be a problem.
Writing here isn’t harming anyone, though Rachel may argue otherwise, it’s just voicing an opinion.
Looking at Edie’s dad’s profile... where’s the harm? It’s not affecting his life in any way and if all you’re doing is having a look at his public posts, it’s not harming you either.
I do think that the vast majority of people these days understand how to lock down their profiles on FB. I personally think that the fact he hasn’t speaks volumes.
There’s nothing about Edie (or the other girls) on there that you can’t see on Rachel’s profile anyway (and much more besides). As long as you’re not messaging him or sharing his posts or otherwise causing harm, I don’t see the problem