I think mainline pilots are in a different boat, longer career stagnation has meant securing new aircraft is a higher priority. Losing the SH replacement aircraft would probably add another 10 years onto wait times for upgrades and promotions and deny a career command to a few hundred pilots.
There’s also a general awareness that they are better off than most of the subsidiary pilots, even after new variations. Whereas the subsidiaries are a lot closer to Award conditions, meaning there’s not much incentive to outsource.