I believe that the guaranteed percentages are set by the league with the fist and first half of the 2nd round being guaranteed. There s a sliding scale from 97% to 67% for the last half of the second.
I think the issue was the normal participation agreement that the team wasn't willing to sign before he passed a physical.
If the injuries are bad enough, the team might not even sign him. Given the videos that doesn't seem to be the case.
The apparent non-disclosure of injuries may be a league and union issue with the agent.