I would think it's a victory for Ollie, but either way, "just cause" had to be defined somehow and the definition in the contract above doesn't seem unreasonable. That could be why the arbitrator ruled that way (so as not not to be overruled). It's not like it limited "just cause" to killing someone. It specifically referenced "serious noncompliance with NCAA rules or regulations."
UConn definitely seems to have some good evidence that Ollie committed "serious noncompliance" considering the NCAA's findings. And the noncompliance was committed at the time of the violation, not at the time of the NCAA findings. Also, being an undefined term, it's arguable that the NCAA's findings, alone, show the noncompliance was serious. It doesn't matter if the NCAA was right or wrong, or if UConn fought the NCAA hard enough. KO gave UConn just cause by taking the actions (or omissions) in question. We lost a scholarship and are on probation due to KO's actions or omissions, which means they were serious.
KO was clearly in a better position prior to the NCAA findings. He had the argument that they violations weren't true OR they weren't serious. I guess he can still say they weren't true, but that's tough. I'd think that KO's only defenses are: i) UConn fired him before the violations were known to be true/serious and he should have been suspended (with pay) until that time. ii) UConn deliberately rolled over and let the NCAA do what they wanted just to benefit UConn. That still doesn't mean that KO's actions don't represent serious noncompliance, just that UConn would have to prove it again. iii) JC committed the same/similar level of noncompliance and wasn't fired so the violations must not be serious. iv) even if the violations were serious, JC not being fired shows that the reason KO was fired was performance NOT for cause. That shouldn't matter, but it may being a union contract, plus they are just going for the "looks bad" factor.