Okay, you have to admit that's a pretty contrived example. Firstly, most people are not going to run for anything in 20 years. The chance of that alone happening is pretty slim. Secondly, how would that complicate my hypothetical run, anyway? If we were going to go by this insanely arbitrary requirement, then everyone in the US will most likely have a photo with someone that ends up on a no-fly list. It's really easy to be in photos with other people, you don't even have to know the person. So what, I knew someone 20 years in the past that had since been put on a list. That has absolutely no implications of my actions or connections in that present day. That said, I could see how the media might react, so that part wouldn't be too far off base in that regard.

But if that's the best argument against it, then I continue to not care about what I put on Facebook. If it comes back to bite me in the ass 20 years from now, then I can deal with it then. I'd rather not completely destroy my social life in the present for a hypothetical scenario that will probably never end up even happening.

There are plenty of examples of successful politicians being former friends with actual terrorists. A facebook photo seems unlikely to make that any different.