Hehe, it does sort of look like he's waving which lowers the threat level just a tad
The first thing that came to my mind for use as a reference for one of these (if you are interested) is a Rock-em-Sock-em-Robot. Of course I would modify the arms to be more rock-ish. The other thought was 'The Thing' from the Fantastic Four but you are already pretty close to that. You may need to carve in the joints between the rocks on this guy to lessen the marshmellowy look he kind of has. You know, rough him up a bit.