Having taken a look, I agree that these are comments on a post, not Facebook Messenger as some claim.
However, whilst he is commenting on posts made prior to her disappearance, his comments were all posted after her disappearance, so the allegation that he was bothering her is wrong. He seems to have upset some other people who have posted following her disappearance, but that is another matter.
His profile does not include a picture of himself, so those identifying someone in a photo as him are guessing.
Being a little bored, I've scrolled through his posts. Contrary to what is said, there is nothing on there about abduction.
It isn't even clear if he lives in the UK. His posts and reviews suggest otherwise, although that is not conclusive.