Re: Respect/Lack there of.
As with all things, there are always at least two sides to every situation. One is the side of intent, the other is the perception of that intent. I cannot speak for the perception of this situation, but I feel confident that I can speak for the intent of the Nidan in this situation.
Although I was not present during this event, I have trained with this Nidan since his first day as an Aikidoka. Through the years I have never seen or felt any disrespect in any way shape or form, either to a dojo member or a guest. This particular Nidan is always one of the first to engage any guest or new member with previous training as a person that can offer new insight into the world of Aikido and relishes learning anything new from anyone.
I have on occasion also been asked to substitute for the dojo-cho as well as other sensei in another dojo. I admit that I may be somewhat ignorant to all of the etiquette that is needed to not offend any given person. if given the same situation, my first priority would always be to my sensei and the well-being of the dojo. To allow someone who I know absolutely nothing about to take over the class would not be looking out for my dojo-mates or the dojo. I am sorry to say that even though you and I have lived in the same town for many years, and I know "of" you, I have only had the pleasure one or two times to train with you personally. With what was previously suggested about vouching for and taking responsiblity for someone of this high rank, I would have to say that I still do not know enough about you that your vouching for this shihan would be enough for me to put the safety of the dojo at risk if given the same circumstances.
From reading all of the previous comments, it would seem there are many opinions, all coming from one's own personal perception. I do not know who is the most right. I do know that this particular nidan is one of the many very respectful people I have trained with in aikido. I would suggest that somehow the perception was skewed by some expectation that was not in his power or authority to meet.