Ahh, I see what you're saying. I took "can't apply" too literally, my bad. What you just said is a reasonable and valid concern.
The way I look at it is that solid MD applicants will likely not be shooting for community programs in relatively uncompetitive locations (for the most part) after willingly completing whatever the required OMM competency certification is. In addition to that, they'll be applying with DOs PDs reading their app. On the other hand, top DOs will be able to apply to ACGME programs they could potentially match at but don't because of the massive gamble on backing out of the AOA match. It will help those top applicants with a total package - scores, research, letters, etc.
With that said, there will be some competitive MDs that want the previous AOA spots because of location, program ties, etc. It'll be interesting to see how it plays out. Personally, I'd take the hit of losing AOA spots to apply to ACGME programs concurrently but that's because I'm heavy into research and university programs interest me.