Not to worry, they have the Ashtiname. I think there’s a copy in Istanbul as well...
The place has survived because muslims believe that document was signed by Muhammad.
The idea that the site’s defense rests on all muslims knowing about the Ashtiname and not having a knee jerk homicidal reaction to it’s being a Christian site is not very comforting.
There is a doc that was signed by Mohammed’s hand since he could not read. That is why it was and is left alone by the Muslims.