This sounds almost like a tautology or a "no true Scotsman" argument. If "insecure" <=> "condescending" by definition or "well, if he's bad mannered he can't be really secure", there's not much to argue.
true, but the juxtaposition should then have been between "insecure" and "secure", not between "insecure" (personality trait) and "excellent" (skill level).
It's possible that you just may be insecure about your comfort zone of categorizing things ;)