Not a Southern Pilot, but insider enough in the industry.
Southern had nothing to do with 5Y. The money comes form independent sources. But in the present economic environment it is very well possible that Atlas plans to buy Southern.
It is also not inimmaginable that some 5Y routes were subcontracted to Southern, but to see direct industrial action in that would be a little immaginative. That happens all the time. But, on the other hand, with Atlas you never know...