I sense a circular definition here. Aikido is non-violent, therefore an act of violence committed by an aikidoka must be either (a) not aikido or (b) not really violent.
But that position, I think, gives aikidoka too much credit, and students of other arts too little. There are plenty of peaceful students of other arts. There are plenty of not-so-peaceful aikidoka.
Aikido is a martial art. Like a sword, it has the ability to do great damage. But like a sword, the violence is in the hand that wields it, not the sword itself.
Yes, I would say an act of violence is not Aikido.
I don't see it has anything really to do with giving credit. It's a totally different art in essence. The purpose is Harmony rather than control, being at one with rather than against etc, etc.
Of course many can and indeed do take what they can from it and use it as a means of combat, defeating the opponent, or any other purpose employed by other martial arts. Thus Aikido gets denigrated in my opinion.
Aikido is like a sword? I would say it is like the healing sword yes and thus needs a person of right mind to wield it properly. So yes, it's the person who needs to change in order to do so. Hence the path of self development rather than self defence. Self defence in Aikido is merely a powerful by product.