'ltn and beyond' - I hope that too.
However, as is frequently made clear by Hand Solo and/or Tandem Rotor, it is up to individual company councils or similar groups of pilots to put their own cases forcefully enough to prevent any such threat becoming fact within their own airline.
It's difficult to see in reality how any cross-industry grouping from more than one airline can legally (even supposing they wanted to, and BA have not demonstrated much history of that) take industrial action on behalf of different carriers.
However, the BACC line that any group of pilots, by electing and supporting a strong CC in pursuit of their own best interests, can maintain their own Ts and Cs where they wish...is actually broadly correct, and regardless of OS, Jetstar or anyone else will in theory always be effective.
In the meantime, it's difficult to see why any of us wanting to improve our own situation should not join OS if we so wish - otherwise we are putting the interests of others before those of ourselves and our families.
I leave it to the forum to decide - (assuming this post is allowed any longevity) - whether BA pilots have genuinely and collectively ever demonstrated such commitment to non-BA pilot groups.