I'm a little curious about this, so I hope you'll indulge me a little
Gozo Shioda explains several times that Aikido used in actual combat requires punches and kicks (surely that's "resistance"?), and also has the famous "Aikido in a fight is 70% atemi". You also have offsprings such as Yoseikan and Tomiki Aikido.
Isn't it a bit much labelling ALL Aikido as "pure non-resistance"? Certainly I believe there are styles where that is the main goal, but surely that can't be said about all Aikido in general, can it?
Read Sensei hasn't answered, so I'll fill in a little bit of info: he's the dojo-cho where I train, and we do indeed use a LOT of atemi (we are actually somewhat infamous for accidentally bopping people when we train at other dojos, because we expect uke to move). Sensei will correct me if I'm wrong, but I think a lot of it has to do with intent.