I'm afraid you are mistaken. Draeger was dan-ranked in Shodokan Aikido, and according to Ellis Amdur, was very good. And beyond judo and iaido, he was highly ranked in kendo, karate, Shinto Muso-ryu Jo, and Katori Shinto-ryu kenjutsu.
Perhaps there is an oversight on the part of Mr Draegers biography/ies on the Net no mention is made of him training in Aikido.Any biographer worth his salt would surely have mentioned this if indeed he studied the art.There is of course confirmation that Mr Draeger was proficient in the above arts mentioned by you.
Whether or not he was an aikidoka I consider him mistaken when he states that atemi has been removed from Aikido.