Why focusing on Western? Any DO school is going to have its share of people who would've rather gone MD for whatever reason so I don't think that's specific to Western. And it's not like the 'MD rejects' are whining everyday in class about their failed applications... they'll be studying their butts off just like you will be, and sooner or later they're going have to accept their degree route.
If anything, due to the huge in-state applicant pools graduating from the UC system, Stanford, Cal states, etc the CA DO schools may have more applicants/matriculants who are also competitive for MD schools and may have even gotten into MD schools outside of CA but in the end would rather stay in Socal for medical school.
In the end I think that if someone is well-informed and still truly not happy about going DO instead of MD then they should do whatever's in their power to go MD. Seriously.