The couple shouldn't have been occupying reserved seats - but taking a photo of them and putting it in the public domain is absolutely disgusting behaviour, and makes me wonder about the whole story. Anyone who would do that would be capable of lying about anything.
The only thing to do in this situation is tell the ticket inspector that someone is sitting in your reserved seats and refuses to move. They will sort it out (as they did in this story).
The public shaming is despicable, and it's so sad that someone's first thought is to take a photo (without someone's consent) and put it on Twitter. That is far worse than taking someone's seat. The couple's "posh" voices are neither here nor there.