The object of having a local union and IFALPA - to having any union presence, actually - is to expand the power of the individual.
I have posted a suggestion elsewhere about the future of the AOA actions, but may I suggest that you take a hard look at your own benefits (past and present) achieved by a union's presence (or absence) and base your future decisions and thought processes on that.
In brief, you should justify your actions on whether you support the concept of a union or not.
If you do, then you can refuse the offered position with a clear conscience.
If you do not, then you have to decide for yourself whether you think your future employment chances will be affected by the label "scab" being attached to your name.
Personally, I think that the AOA is clinging to a poor position AND that allowing internal upgrades totally destroys their credibility (since they are themselves filling the vacant positions they are fignting against), but as long as the AOA Membership as a majority stand by that anomaly by emptying their own wallets that is their own business and their decisions should be respected.
Generally speaking, the strongest organisation is that where dissention and argument is thoroughly thrashed out privately in the meeting room and the individuals emerge with one voice regardless of personal conviction and remain silent about the differences of opinion.
I hope the AOA Executive and Membership can find a way to conclude this sad state of affsirs in an agreeable manner.
I hope that helps.