I will not pretend there aren't MANY programs who need to contract or close down.
However, I would point out that not all programs who have opened up recently or expanded have done so for nefarious reasons, as others frequently have said.
When I was in med school, I encountered an attending who was planning to open a program (and subsequently did). It didn't strike me that he was doing this for the cheap labor, but rather that he genuinely wanted to be able to teach and have an impact on the next class of residents -like the reason many people have children. Back then, the sky was the limit for rad onc and residency expansion wasn't on many's radar -on SDN, most of the forums were of the 'do I have a chance to match?' variety. By the time the residency opened (4 years later), the tide had changed... but a lot had already been invested by the institution. I would guess this is the case at many places who have recently opened/expanded.
Regarding why chairs are desperate for their programs to fill... I couldn't say for certain, but I would guess it has something to do with the fact that there are a hoops they need to jump through to get a residency open, and not filling those spots would make them look foolish among their peers (and maybe make some in their department lose faith in their leadership). -thus it may be vanity rather than greed.
I don't know anyone training at USCD, but I can't imagine it would be impossible for them to find work -even in SoCal. Mundt is a huge name and probably won't be shy about picking up the phone... and that matters moire than a lot of other factors.