As if naming others to do something wasn't obnoxious enough.
This pretty much sums things up. As foolscap001 said here and jmaynard said here the inclusion of the bit that says if you don't post it you are a bigot by implication is objectionable. The intention might be the good, but the execution is of the annoying "repost this or else" type that is quite off-putting. It's even worse than the annoying "Name five people to..." bit.
Consider the following example:
If you truly believe in a round earth, then re-post this and title the post as "Round Earth". If however you believe in a flat earth, then just ignore this. Thanks.
So how many people, for whatever reason, simply wouldn't see that, or would see it but decide that they have good reason not to re-post it and thus be seen by implication as flat earthers?