They diverted because it would have contravened a union contract? My airline has been called militant in the past but we have the good to start, good to finish rule.
I'm actually pro union, but in the US you can't get a contract without a union so have to pay dues for the contract negotation. You can pay more to be a full member which I didn't elect to do. I think crews have to remember that we're here to serve the flying public and not the other way around.