You're right ofc, but I don't think that's what's going on here.

There's the well known chinese emperor who's name escapes me who's tomb has been left for exactly this reason - if we were to excavate it would be very difficult to preserve the contents. I doubt that's what's going on in this location though - I imagine the taliban or whoever runs the show there would very much appreciate the short term cash flow from opening a site like that.