Barrett is a known blowhard. Don't let him bother you.
He uses two very poor examples to brush the entire profession in a negative light. Cranial probably should be removed from the curriculum, sure. But the presence of cranial does not invalidate all of osteopathic education, 90% of which is identical to its allopathic counterpart.
And, where is the evidence backing his claim that more DO's promote chelation therapy than MD's? 99% of DO's that practice chelation therapy in their lifetime do it for the same reason that any MD would: treatment of arsenic poisoning.