It seems to me that the document was pretty demonstrably proven to be a hoax. You can find the arguments and evidence online, I'm not really in a mood to hash it out here.
But anyone will believe anything they like. If you want to believe it isn't a hoax you have to contend with the typographic and other anomalies that seem to show otherwise.
Yes, documents are online but how you can prove that those are hoax? The last analysis I know the guy made cross reference checks using modern search engines and newspaper databases and things where matching. I don't want to say that documents are real but for sure I never saw any argument that would definatly say that it was hoax.
I said I believe it's a hoax. I never claimed to be able to prove anything. I believe the evidence that purports to show that the documents aren't genuine, which you can refer to. Even a lot of people in the UFO community don't find the Majestic 12 documents credible.
You can't prove they're real, either, although you might believe they are. On balance however there seems to be more evidence against them than for them.
But anyone will believe anything they like. If you want to believe it isn't a hoax you have to contend with the typographic and other anomalies that seem to show otherwise.