It's not impossible, but I'm very wary of this one. The "best wishes" looks like the way Freddie used to write it. I'm not going to call fake, but I'm edging on the "unlikely" side of the fence.
Its the mention of 'Queen' that I find bizarre. And the fact he must've been in public to write it.
Lol, its bollocks, if you do a google John Deacon Autograph, there is a site with John Deacon Queen 2011, 2001, 1999, 2008, all on the same photo.