That was his point. Schools by convention don't report USMLE scores, because if they did so, they would be hand-tied in terms of trying new things out in the curriculum. There would be no variation in classroom time, no trying out things like PBL, early clinical exposure, and whatever else is being tried out that academics think will help make folks better doctors. Every school would be identical and it would all be "teaching to the boards", like some of the offshore schools try to do, something all agree doesn't make you a better doctor. So schools want to be free to work through various educational changes, and don't want you to use board scores to select schools. As it stands now, all schools will cover the same material in some fashion that will give you a good foundation when going into board study, but the real studying for the boards is going to be your own effort. You will have access to the same First Aid, the same qbanks, the same board review series of books, and will spend 4-6 weeks studying hard over a summer, reinforcing and building on what you learned the prior 2 years. So board scores are really an individual effort, not something the school has a huge role in. To the extent some schools historically do better than others with any regularity, I would ascribe this success far more to admissions than teaching -- if you admit folks with the right combo of brains and work ethic, they will do better. The teaching is mostly self teaching, so self starter trumps better lecturers any day. Heck some folks who do really well never attend lectures.
And yes, from my experience ALL med schools are going to claim they have above (national) average board scores. There is no one able to question that, so they freely seem to say it. Half are lying. So I personally would ignore those comments.