why the need to find the treasure?

OK, I get it, its a movie, so any excuse to go treasure hunting is a good excuse, but....

Realistically, was there any need for Ben to find the treasure to prove his ancestor's innocence?

Here is how I have it: Patrick hears from his grandfather (the child in the prologue) that some men, who were later revelaed to be KGC, approached Thomas Gates about solving a cipher. Upon finding out they are KGC and after a treasure, Gates burns the diary, along with it the cipher. While there is no 'proof' of this story, it is accepted as truth, and years later, Thomas Gates is considered a national hero (or treasure :P).

Some pages of the Booth diary remain all these years later, and presumably these have been tested for remnants of a cipher or treasure map but to no avail. When Wilkinson comes forth with his page, which lists Gates as the 'artifex', this trumps Patrick Gates's story and Thomas Gates is labelled a conspirator.

In an attempt to disprove this theory, ben Gates runs tests over the newly found page, and successfully reveals the existence of a cipher on it. Surely, the mere existence of such a thing proves that the intention of the Booth/Gates meeting was for Gates to decode the cipher, or at least casts a reasonable doubt upon Wilkinson's theory.

And if the existence of a cipher is considered not enough, why on Earth should the existence of the treasure be considered enough. The argument is whether or not Gates was planning the assasination of Lincoln, or whether he was trying to decode a cipher. Whether or not the cipher leads anywhere is irrelevant.

"Unless you find the treasure, this does not prove anything" - Abigail

Why?

Cheers in advance

Bender, honey, we love you
Shut up baby, I know it!