There are other ways to support besides an SOS/sympathy strike. At the very least, pushing to keep the JS (even if just in the cabin) can go a long way. Offering buddy passes, even offering to pay the fee for them in extreme cases, as well as offering places to stay and rides for stranded pilots, etc, are an absolute bare bones minimum other pilot groups can do. Depending on the circumstances, and even though it is a "different union", I'd even be willing to pay an assessment and certainlly would contribute to their emergency family fund or whatever.
Honestly, we can't afford not to. If they are gutted in such a way that turns them into a top 3 scopeless B scale outsource machine, every section 6 from now on will have to compete with that. We can wax over the woes of not being in a "true trade union" all we want, but soon may not be the time to be barfing 50K per kid per year on worthless degrees in feelings and culture with zero ROI ever while pretenting we can't afford 50 or 100 bucks a month, or worse...pretending its not our fight, for an effort with an outcome that has more to directly do with us and our family finances in the short and medium term than just about anything else.