And here I was thinking it was some kind of big secret or something.
If the symbol means to push the boulder, then the boulder must have been one of the original traps/detourants placed after the Jedi was buried. Did the cultists push it out of the way and then place it there again?
Cultist 1: "Hey, Carl?"
Cultist 2: "Yeah?"
Cultist 1: "Come stand in front of this boulder. Make sure it don't move."
Cultist 2: "You sure about that? What if someone comes?"
Cultist 1: "Don't worry about it. Just stand there."
Cultist 2: "Sure thing."
Cultist 1: "Man, I hate that guy."