His initial claim was that milk makes your bones weaker because it raises the acidity of your blood and your body uses calcium from your bones to counteract that and return to balanced Ph, he has since backpedalled into saying that milk doesn't make your bones stronger because the study he linked found, I paraphrase, "no association between (...) bone fractures and the consumption of milk". He's moving goalposts, that's why he feels that his point still stands, which is fine - everyone suffers from confirmation bias, hence the peer review system - in this case, we're the peers.