What this sounds like is that with more widebody flying on the Tasman there is less and less flying for JC crew. Thus the rumoured solution for them fly domestically seems more about keeping them working efficiently. The secondary benefit of assisting with shortages of mainline 737 crew is great in the short term but you can perhaps forgive mainline crew for being a bit cagey given how the Jetconnect operation has contributed to the adverse impact on mainline careers over the last decade plus.
Slight problem is that one Domestic sector activates the FairWork Act and implies they must be paid as Australian Pilots under the Short Haul Award. The Company has outsmarted itself! What do they want efficiency or a Lower Cost base? You can't have both!