For sure, there are plenty of people that score well on USMLE step 1 from DO schools but there is also a lot of self-selection involved in who actually takes the test since it's not required at DO programs. Also, my comment was regarding aggregates, not individuals. MCAT correlates with step 1 so, on aggregate, one could reasonably expect a class with an average MCAT of 32 (CNU) to do better than a class with an average MCAT of 27 (average DO schools).
I would also disagree with your statement that curriculum is of paramount importance to preparing for the board examinations, I would say that individual preparation for the exam is way more important to doing well on USMLE. As an aside, mandatory attendance is becoming less and less common and average performance on the boards has only been increasing. Seems like a hard sell to say that increase in performance on the boards is due to improvements to curriculum nationwide rather than increasing competitiveness of medical school admissions.
Anyway, that part of my post wasn't really something I have strong opinions on. I'm more interested in hearing from faculty members here about why they think CNU will collapse and the relative merits of attending CNU vs DO school based purely on career prospects rather than on the effect of for profit education on medical education.