I have no interest in for-profit schools, for philosophical reasons! I really would hate to go somewhere where maybe my attendance was made possible because someone more qualified simply could not afford to attend (which is very different from being able to attend, but choosing not to spend the money).
I get why you defend the business model, but I think your comments are a little disingenuous because I think you really do get it, and I don't think there is any chance in a million years you would ever allow your kid to go to CNU.
The irony is that, apparently, everyone at CNU is playing themselves since it seems that nobody there is fooling anyone, and, while you note most folks there could probably go DO, it turns out its match list looks just like one from a DO, so they are apparently not getting the MD benefit they seek!
To directly answer your question, no, I don't think it's a good thing for a for profit school to be skimming a few full pay students away from the not for profit sector. There is no meaningful reduction in competition, but there is a draining of dollars into the pocket of investors and away from non profits actually fulfilling a mission.
As for me, although I am not ready to apply, I still have high aspirations. Consequently, like your son, I don't anticipate applying DO in my first (and hopefully only) cycle. Also like your son (I suspect), I would never apply to CNU because it won't be able to prove itself during my time horizon, and I didn't post what I posted only to be provocative; I really do believe it. And, no, I have no idea whether it will succeed, fail or be bought out, but I do think in the short and intermediate term there will be a stigma attached to graduating from the only for profit that only attracts people with no other MD options (this has so far been borne out by the first match results), and this is notwithstanding what the proud parent cheerleaders come on here to state.
If I am unsuccessful, I will include DO in my next cycle, and will never have the opportunity to take CNU because I would never waste the time and money applying. The posts on CC a few years ago from the parent whose kid was accepted to their BS/MD program, after which they started repeatedly harassing him for their significant, non-refundable deposit even after he turned down their offer was a real turn off for me and told me all I needed to know about CNU.