He’s also wrong about aloof coming from Dutch, or at least the OED contradicts his explanation, but he can be forgiven for that. The second edition of the OED agrees with his explanation that the word comes from Dutch, but the third edition changes the etymology significantly. The third edition entry was revised in September 2012, probably too late for him to have seen it before publication. (There’s no excuse for the eleventh century thing. That’s so bad it’s not even wrong.)
Aloof is sixteenth century and probably immediately from the French au louf. The Dutch is cognate, but probably not the origin.