+1 to giving interactive items different resistances.
I'm more curious why there's a giant stone boulder hanging right there in the first place.
The boulder is tied to a makeshift wooden crane. It looks as though the mechanism lifts it and lets it drop - and has already done it a few times because the floor is already cracked. I assume some other tomb robbers (before Gimblebok's team) failed to get the doors open, and decided to get creative. There's a door to the chapel right on the beach so they knew there would be some room/hall/hallway underneath the stone mosaic.
