this isn’t that hard. First you got to Southwest no matter what. If things slow down tomorrow you are a destination carrier. Second. Go to the next conference. Let the United recruiter know you really want to be at UAL but have an opportunity to go to SWA and have a class date of XX/XX. I am willing to bet that you get an offer to start the interview process within 2 weeks of leaving OO. Just update your app with your new employer. After that settle into SWA. Forgot about United except to update your app every 30-90 days. United might never call. United might not call for years. Make your choice then. Also depending on your age, marriage status’ kids…..of these things change the desire to leave or stay at SWA.
If you aren’t married, don’t have kids yet, in your mid 20s, etc the reality is you have no idea where you will live. I live in Texas. I went to JetBlue back in ‘07 and lived in the Northeast. I never planned to live in Texas. Yet here I am at United living in Texas based in Houston.