Honestly, I don't think Delta style scope is all that valuable to SWA. RJs only work when they're part of a hub-and-spoke network that is primarily structured around feeding wide-body international flying. With a predominantly point-to-point route structure, a bunch of RJs would do SWA virtually no good. There's a reason that SWA management has never pushed really hard for it, and it's not just because they're such nice guys.