A bunch of dirty parchments and papyri with chicken scratches on them would have excited zero interest, unless they needed to burn a few to keep warm . . .
The thing I don't understand in all this speculation is that the Roman government of A.D. 70 was not Christian - indeed if anything it was anti-Christian. Why would the Vatican wind up with any surviving treasure - if indeed the Goths or the Vandals didn't get it?