There are a lot of '59 clone builders who are anonymous by choice, probably including some people on this forum. (Probably -- they don't come right out and say they've put Gibson logos on some of their work.)
It really wouldn't surprise me if some people have specifically cloned Max's and Derrig's clones.
The best other builders are at least as good as Max was. But Max has historic/collectable value above and beyond the quality of the guitar. An unknown builder isn't worth as much as Max, and provenance is important.
If the seller had letters, emails, receipts, a cleared check made out to Max, an appraisal (especially by someone related to Max), pics of him with Max and that guitar, anything more than "just trust me". But to me, " just trust me" isn't enough.
And if you ever sell, "trust me because I trusted someone else" is even less compelling proof.
In the '80s and '90s no one knew Max was going to be a big deal. Completely understandable that some people didn't keep documentation.
But by 2008, if he doesn't have a story like his house burned down with all the documentation in a file cabinet and the only thing he could save was the guitar, it's unbelievable to me that he doesn't have a scrap of proof. (I'd need to see his insurance payout on the house and a newspaper clipping about the house burning to the ground or similar.)