Here's some grist for the mill.
https://skift.com/blog/largest-fligh...spirit-merger/
AFA is gunning to win over the B6 FAs and kick out TWU if this merger is approved. Sara Nelson is well regarded within the progressive left wing and was even floated as potential Secretary of Labor for Biden, so there's some political heft to this endorsement. Taking detrimental effects on labor off the list of reasons to block the merger doesn't hurt either.