I'm in agreement.
In terms of provenance, let's say this guy has "extensive info". If I were him, I would likely not put in the public domain of the internet. Keeping the secrets secret enables more robust proof. If every Tom Dick and Harry knew what to forge, you are damn sure they would forge it.
Sure, having a high price and no real provenance on ebay makes for great fodder, but it also keeps all the looky loos from harassing the seller. If I was a serious buyer, my questions would be serious and not on ebay.
If I were selling a 25.000$ bike I'd do it through a renowned seller of vintage bikes to provide credibility without baring it all. Like they do with art galleries and independent controllers that check for looted and forged pieces. Maybe the bike world has something to learn from the art world in this case. Who knows.