There are a number of complex issues in the circumstances of an unprotected "strike" - or any other breach of contract.
This and the other thread have overly focused (IMHO) on the issues to do with the individual.
Unite will not/do not care about the individual. They never have cared for an individual in this dispute. Unite will care about their own legal and financial position - i.e. Litebulbs' subs.
There is another branch of the law - entirely independent of the TULRA stuff that Unite will have a concern about.
That is the potentially unlawful act of inducing someone to breach their contract.
If any "Official" of a TU induces someone to breach their contract outside a protected dispute, BA can take that official, and the TU, to court for all and any costs and losses arising from the breach.
Unite are very aware of that, and can and will stop the bassa junta from doing anything that opens Unite's finances as a piggy bank for BA.
That's why Unite disowned the bassa letter about the window blinds - within 24 hours. Staff must follow a reasonable instruction from their employer, no matter what the local branch might think.
At least the Unite lawyers can stop the wilder acts of the heritage junta. That legal framework also explains why the bassa junta's ideas about guerrilla action just will not work.