I think there's more to this than just being 'arsey' about his choice of pronouns [they're nouns actually..] and refusal to remove them.
Look at the reason given for suspending and sacking him:
He was suspended and eventually sacked after repeatedly refusing to remove his protest pronouns after bosses warned that they posed a “serious risk” to the transgender community and the council’s reputation. [my emphasis]
It is obviously nonsense to suggest that by using mocking but accurate pronouns this worker was in any way a 'serious risk' to trans people, it sounds like our old friend 'literal violence', doesn't it?
It's also a very serious accusation to make against a worker - not that they are being arsey or a dick, or refusing to follow orders, but that they are behaving in a threatening way, posing a 'serious risk' to members of the public.
Being asked to remove your choice of pronouns because they are irritating and OTT is one thing; being told your are behaviour is so dangerous and threatening to trans people that you're going to be sacked is something else.