I heard of this on the news this morning. Whatever the rights and wrongs of this the RMT representative who provided comment did nothing to gain public support because he gave no indication of the specific nature of the grievance(s). I then went to the RMT website, again plenty of angry rhetoric but nothing to explain to the public (who may be inconvenienced by this action) exactly why we should have sympathy with the RMT's position.
If you're going to inconvenience the public - to whom you are paid to provide a service, basic decency suggests you explain why. An additional benefit might be to have more public sympathy for your cause, which could only help you politically.
Edited to add: Just seen the RMT guy on the lunchtime news. The RMT really need to sort out their PR - I saw nothing but a rant. I'm, no further forward in understanding the RMT's case.