...is that different "mode" specifically tied to the act of bowing?
All cultures have customs that separate out various activities from each other.
The question is not whether or not some action of Japanese etiquette has a benefit or not, the question is whether that specific activity is necessary to the act of training in Aikido.
Let me say here that I have nothing against bowing, wearing funny clothes, or whatever - I do all of that on a regular basis (although there are plenty of times when I don't).
What I am saying is that there is no intrinsic requirement to perform those activities in order to be doing Aikido.
I am with Chris here.....if I am on the street and someone comes out of the dark at me with intent to do harm and I don't have time to bow or put on my funny clothes.......though I bring a peaceful conclusion to the situation after turning.....moving.....and applying what I learned in my 40 years of Aikido mat time......is that not Aikido?
Of course it is a given that some of the things I have learned over the years would also result in safe conclusions for me alone that some here might not consider Aikido.....but that doesn't change it for me.