Right, the contention brought to the labor board was that it was a collective action that went against the contract. It's not clear that the union as an entity

Right, the contention brought to the labor board was that it was a collective action that went against the contract. It's not clear that the union as an entity was involved in that collective action. Edit: expanding a bit, laws around collective bargaining include elements around not having to deal with multiple entities - if a union is representing workers, it's THE entity representing workers. If workers have a problem with the union they need to handle that internally, but they don't get to say 'the second shift guys decided they want to negotiate separately, so now you have to go negotiate with them as well.'