I hate it when people beat up on the levels. (Sorry, had to do it.)
I think you and I are on the same page with this. I've not had anyone as significantly affected as the example you give, but I did have someone come to a series of workshops I offered who'd had some severely bad experiences. She toughed it out, even though she needed to stop and cry every time someone touched her neck (her experience involved an actual "rape choke"). She didn't join classes long-term, but made decent progress in the few weeks of the seminar series. It took a different approach to help her get started, and her discomfort was very different from those folks who just danced around topics.
Ya got me... I didn't proofread it.
As to your student.... PTSD is a ... well fill in the blank.