I may have spoken too soon... while this solves part of the mystery, it doesn't solve all of it. Right now, if I do a search on ITA for *any* nonstop flight from RDU-IAH after 12pm on Friday March 11th, absolutely nothing shows up. No CO or UA..
If these flights have been re-marketed as UAX, they should still show up in a generic search, right? As of right now, I can't see how anyone anywhere can buy these flights, which sort of implies they don't really exist.
So yeah, I'm still missing something. ;-(