Most are designed for the cover to move to the side when deployed but some are designed to split in some way that could cause the rhinestones to come free.
An airbag is just a carefuly sized explosion instead of a kevlar pillow case, in a crash the airbag is deployed in a fraction of a second, lots of engineering goes into making them safe. However, the rind sones aren't an intended part of the system and can be separated from the wheel and "knocked" out of the way at high speeds, much like ball barberings in a claymore.