We've always had a history of making sick jokes in the UK following some disaster or unfortunate incident. The good ones make you smile despite the subject matter - the bad ones just make you say to yourself "tosser" and that's it.
This joke and the tosser who posted the "joke" definitely fall into the latter category. But to go as far as arresting him with a view to prosecution is itself a sick "joke". Can the police be prosecuted for wasted police time? Cos they bloody well should be.
It is a sad state of affairs when the Police waste their time and tax payers money persuing something as trivial as posting a stupid joke/comment. The most that should have happened, is a request to FB for the removal of the offending post.
Way to go plod - and they wonder why the public has so little respect for them these days...