USAirways needed to sell off MidAtlantic to stay liquid and hold on long enough to be bought out.
NWA, on the other hand, just posted a huge profit and is far from having a liquidity crisis. There are also ALPA contract restrictions that prevent NWA from selling Compass until NWA has 10 of a new type of narrowbody aircraft on the property (they haven't even placed an order yet). Certainly, under the right circumstances, it wouldn't be impossible for those restrictions to go away under a new TA, but I see no reason to think that will happen in the current business environment.
NWA does not need the cash in the near term, and since Compass currently has only 5 or 6 aircraft, but another 30 on the way, it would make little sense for NWA to sell off Compass now, in it's infancy, when they would be able to get far more money selling it as a mature operation.
Also, when the time does come to sell I'm not so sure NWA will be interested in selling the operation as a whole to another carrier, when they have done so well in the past selling regionals through IPOs. E-jets are becoming very popular, and Compass stands to be the only real competition to Republic in the US regional E-jet market. I'm sure NWA knows that, and they're probably willing to bet that Wall Street will notice too.
So, basically, Republic might want to buy Compass, but I seriously doubt Compass is for sale.