As far as I can tell everyone involved is offering more than just this follow you business, it's the follow thing and some genuinely good additional thing, a signed script, the phonecall, Andy Nyman is selling "ghost stories tickets and a cuddle", Dave Lamb's prize is doing your own Come Dine With Me voiceover, stuff like that.
Probably because it's how everyone was wrangled together that there has to be this twitter aspect to it, it's a shame because it seems to be a decent celebrity auction with an angle that a few vocal neerdowells have taken against.