Pure Speculation:
1. Banks not lending = no new airplanes for mainline
2. Delta can't furlough without consequence
3. Staple job for compass increases likely-hood that already trained pilots will return from furlough eventually.

In my opinion it has nothing to do with scope, I suspect that if this were to come about, DAL management would be looking to remove the no furlough clause. Also the scope restrictions that require removing seats would get the axe, which would cost more than the payroll increases if you think about it.