Saying that "I want a seniority system" but then saying that "In case of redundancy I'll be fine because there are lots of non-seniority airlines out there" does appear to be a whole lot less of a 'fair play' attitude than I am used to from Kiwis!
Some appear fixated on the matter of Direct Entry Captains. Every airline that I have worked for has employed Direct Entry Captains and most operated seniority lists. They have done so when there has been a need for captains and there were no possible promotions from within and once existing first officers had gained the experience and were suitable for commands the recruiting of DECs ceased. And all those captains were always employed on the same terms as any other new captains, so no 'undercutting terms and conditions' there. The general attitude amongst those airlines was that promoting internally was preferable as they knew a lot about those people before them becoming captains while captains recruited from outside were more unknown.
Crooked management and training systems can exist equally in seniority based or no-seniority airlines and promotions can be held back in either system, so the risk of 'brown nosing' is just as likely in both That is very much down to the management and their attitudes more than down to what 'queuing' system you have.
About the "new base announced while you're en-route to Athens" situation, I have heard of a non-seniority system that covers anything totally new, such as a new base or fleet, etc., by announcing it with an opening date for bids over a confined period of several weeks, then selecting people from within that group of bids based on date of joining, then after that closing date it's all back to "first in the queue" from then on.
Saul has a good point: variety is the spice of life and every airline being seniority only would be a bad thing. Especially for those from seniority-list airlines that go bust and their pilots need new jobs ...