The players feel that "guaranteed" should mean guaranteed - no exceptions. Once you start putting conditions on it, it's no longer a guarantee.

The players' side of this argument would be: if a team simply decided they didn't want to pay the player for whatever reason, all they have to do is make up something, call it "conduct detrimental", suspend the player for this made-up infraction, and poof - excuse not to pay (or maybe even try to claw back already paid money?).

For example: think about the Kirk Cousins situation in Atlanta. The team signed him to a pretty hefty contract, then for some inexplicable reason, decided to draft another guy and start that other guy immediately. Cousins had NO IDEA they were going to do that, or he have thought twice about signing there. So now, Atlanta wants out of the Cousins deal (don't want to pay all that money for a bench QB). As it stands right now, yes, they can cut him, but he still gets what he was guaranteed. If the team gets the contracts changed to include clawbacks of guaranteed money for suspensions, then all Atlanta would have to do is to do is do what I noted above - make up something, claim 'conduct detrimental', and poof. Even though Cousins did nothing wrong, he's suddenly out a whole bunch of money that they were contractually obligated to pay him? If I were the player in that situation, I'd be PO'd. And then there's lawsuits, and court cases, and all sorts of other nonsense, which I don't think anybody really wants.

And before you ask, yes, I absolutely believe there are some NFL owners who are just scummy enough to try that (claiming 'conduct detrimental' when they player did nothing at all).