He has told me that he cannot form ANY opinion on the authenticity of the document without another like it, of known provenance, that can be used for valid comparison.
John, I agree with you almost 100% of the time, but on this, you are mistaken. Polarik clearly called this document a forgery (in bold text, no less) in his very first post to this thread.
I had seen his post earlier in the thread, and didn't comment, but Horry's reply to Polarik made me go back and take another look.
If you look at Polarik's statement, it doesn't even include one iota of digital image analysis, which is what he's built his reputation on here.
I've got to say that I'm mighty disappointed in Polarik for prematurely stating that this document is a forgery before issuing a complete finished report. I told him so tonight, as a matter of fact.