BYU is requiring the athletes to submit their agreements etc. to BYU for review before signing. "In order for us to best assist you, all student-athletes must have NIL agreements reviewed by the athletics administration prior to engaging in the NIL activity. Disclosure forms are enclosed in this policy."
I don't think BYU can forbid them from signing a bad contract (as long as it fits within the other policies) as part of that review process, but at least they will be forewarned.
https://byucougars.com/story/athletics/1296873/byu-institutes-nil-policies