In context, the complaints about the material itself seem pretty pretextual.
Edit
A frustrating detail here, just in the sense that it's petty turtles all the way down here: the arbitrator found that WHYY's social media policy, which prohibits "inflammatory" speech without qualification, was in fact binding and did provide WHYY with cause to terminate (the arbitrary was vocal about how stupid they felt this policy was).
The reason Grievant got the reinstatement order was that WHYY's HR fucked up their own process and committed to the termination procedure without including Grievant's direct manager in that process. A pure technicality.