I think Lamar is fighting the good fight here. It is ridiculous that NFL contracts aren't guaranteed. Lamar can get hurt, play poorly for a year, then get cut. That is the team's right to cut, but they should still have to pay out the contract they signed. In effect, teams are getting away with signing contracts in bad faith.
If no one trusts Lamar's health, he will get paid less. His (and other contracts) should still be guaranteed. Why would anyone want to sign a contract if one party can violate it so easily? The player's union is getting screwed.