After looking at the photo, it looks like the chip was caused by over aggressive extension of the buttstock, but that's just an opinion. One would really have to try hard to make the buttstock come off with no more damage than that. One has to pull down on the pin itself to remove the stock, not just squeeze the adjustment latch.

The 15-22 is not a combat arm, so I can't imagine getting worked up about it.

BTW, both the MOE and CTR are MagPul products. The only difference between the two is the friction lock. Otherwise, they are identical.