A couple of things here.
First, Tarry. He openly tried to get sacked. Reported in the media that he is being deselected in his seat and is angling to be nominated at a neighbouring seat. Being a "pro union martyr" is his way to do this. He was sacked for a TV interview, not joining the picket line. Others in the shadow cabinet joined and were not sacked.
Second, strikes are dangerous for Labour. Many in the public don't trust them to deal with strikes. The approach that they support a settlement is right, but they need to attack the government more for not negotiating.
Finally, Labour demonstrate again their self destructive abilities. Tories tearing themselves apart, and this muppet decides that now is the time to pull this shit. Same happened in 2016 when Cameron resigned. Tories in free fall, a chance for Labour to make an impression and the right of the party triggered an unnecessary leadership contest. I am no Corbyn fan but that was his window and the party shafted him.