Can Aikido be anything other than defensive? There is no offencive actions in it, even Jo and Ken are reactionary! Therefore, as there are no agresive/offensive techniquies, Aikido must be purely defensive. This is even before you enter the morality argument. Aikido is an art of peace, and even if the techniques seem offensive, the attitude behind it ought to be one of regret at the neccesity of the technique (in the real world) and definately no agression on the mat.
Just the musings of a friday night,