Per the rules cited here:
https://www.buildingthedam.com/2017/5/21/15672310/thomas-tyner-medical-retirement-situation-explained-college-football-oregon-state-redshirt-hardship
If he returns, his scholarship would retroactively count, putting us over the limit.
But there is also a waiver process cited in the following rule.
I don't think CVL's injury would meet that, but I could see a "we just want to suit him up in senior day to get a single shot up" kind of waiver being approved.