How is it likely that Thomas wins his grievance? He had a contract clause that voided his salary and guarantees for conduct detrimental to the team. Not showing up to meetings, showing up late frequently, punching teammates, and sharing confidential team footage on social media, are all right in line with what his contract clause was referring to.
And while I understand the article even references the idea of "guaranteed money is only guaranteed for injuries, reduction of performance, etc.", the reason why this ruling will ultimately be so important, and why you've rarely seen this ruled in the team's favor, is because teams will get more aggressive with cutting players with performance issues over "conduct detrimental", and thus voiding guarantees. They'll start doing so over missed meetings, disagreements, etc.
I would also point you to the Patriots, who recently just "won" grievances with Antonio Brown and Aaron Hernandez. They "won" because they didn't pay out the full guarantees... but they did pay out a substantial amount of them.
They cut Hernandez for, literally, being a serial killer, and they STILL had to pay out a substantial amount of his guaranteed money. It took them about 5 years to get like a $2.3M credit back against the cap. They still had to pay him a $3.5M deferred signing bonus, after he had killed people. I think we can agree that would be considered "conduct detrimental".
They cut Antonio Brown when he had $9M in guaranteed money left, and refused to pay. They settled that this year at about half. I would say his conduct was more detrimental than Earl's also.
Brown's case is probably a good example, because multiple "sports lawyers" I've seen on like Twitter have suggested that, inevitably, they'll settle. If they're arguing over $10M, they'll settle for $5M or something like that. That's usually what they push for in arbitration, so that both parties feel good about themselves in the end.
The other good news is that an arbitrator is unlikely going to let Earl "double dip", meaning whatever he signs for this year, he can't get paid by two teams at the same time. So if somebody signs him for $5M this year, it'll likely reduce the $10M he's asking for by that amount.
That's why right now he has a $10M dead money hit in 2021. That's not likely to change, as that's the proration of his signing bonus, which we almost certainly won't be able to recoup. The question is over the $10M in base salary that was "guaranteed" to him for 2020 that we are refusing to pay.