Yes. You are missing something called the Railway Labor Act, or RLA. Even discussing ANY kind of job action, maintenance write up campaigns, sick ins, not picking up open time, or striking, without going through the "process" can result in the union being fined and workers being terminated.
It sucks, but nothing can be done until the RLA goes away. Unfortunately that will never happen as the airlines like it just fine the way it is. Nothing like being able to treat workers like crap with no fear of job action.