Ok, here is a real life scenario that happened at an interview. I know this because I know one of the people at the panel.

Pilot shows up at a Compass interview and long story short, the panel found out he worked for GoJet ( not by some magic, it came up in the interview because the pilot disclosed it). I don't know the specifics but he was told by the panel that they would love to hire him but upper management would not allow it. The panel actually suggested the pilot seek legal actions.

The reason why you cannot flow from one airline to another like you are able to at RAH, is because of the difference in contracts between all three airlines. All three airlines need to operate, and so they don't want pilots to transfer every time one airline gets a better contract than the other. Plus, this is something that would need to be agreed upon by the Union MECs and Gojet is IBT whereas Compass and TSA are ALPA.