You're just misinformed and wrong.
The union and airline say there's no strike or sick out (job action) because strikes and job actions are illegal under the Federal Railway Labor act. They are unsurprisingly denying doing anything illegal.
https://en.wikipedia.org/wiki/National_Mediation_Board
Your Pilot Career and Scope Clauses - https://www.youtube.com/watch?v=3XYpZg0SPCE