From the launch commentary, the rocket is designed to do a 180 at that altitude for the separation event. So a couple extra rotations isn’t going to hurt anything. Additionally, air density at 100k ft is ~1/80th of sea level, which helps.
Anyways, the stress rocket experiences in a position like that is such that they break up, because its not designed for positions like that - we have seen that on failing rockets videos. This one did multiple flips with upper stage attached that shouldn't be there on rotation. And thats great :)