There is no excuse for treating anyone that way, male or female, young or old, period. It's just plain rudeness and has no place in ones training. If one of my students ever acted that way they would be back at white belt till they showed me they got the point.
Of course the senior people want to train with other senior people at these events. I spend the whole year without the opportunity to train with my ASU peers. If I manage to scrape together the $1000 it takes to go cross country for camp I want to make the most of it. I try to do a class with Ikeda sensei and one with Gleason sensei, I'll book my partners in advance to ensure that I get the most out of my training. But every once and a while a junior student will come up to me and ask if I'll train with them. My response is always positive. They are me 15 years ago. If they get up enough nerve to want to do a class with me then they deserve to get my full support and attention. I was given that support when i was coming along by some very fine people.
We all owe our teachers and seniors a debt for helping us come as far as we have. There is very little I can do to repay them for their kindness. My way of doing that is to turn around and give that same support to the people coming along behind me.
As far as your story goes it represents the worst kind of arrogance. That person had no idea who you were or what you knew. On the e-budo website there was some discussion of Don Angier Sensei's sword videos. There was mention that some people though the first film had too much etiquette. The reply was that for the Samurai, Budo began with etiquette. That was how a society of highly trained killers dealt with each other safely. The fellow you have mentioned shows that he is just a wanna be by acting that way.
I have a friend who has been doing martial arts for over forty years. He has advned Dan ranks in Judo, Tae Kwan Do, Aikido, and hsi primary rank is in Hapkido in which he is an Eighth Dan. He and his wife went to a dojo when he visited the East coast. No one knew who he was or that he had the any background at all in anything. He was treated condescendingly and was not made to feel welcome at the dojo (the head teacher wasn't there at the time). I realized that these same folks (who know me well) would have reacted totally differently had I called ahead and told them who this man was and that he was paying a visit to their school. I then realized that it shouldn't make any difference at all.
My friend saw these fellows in their true form as snobby seniors, full of themselves and their special priveledge in training with a wonderful teacher. Those not so fortunate didn't deserve notice in their minds. This is very bad attitude. And in this case they lost the chance to really meet and get to know a man whose martial experience dwafed theirs collectively. I felt sorry for them.
On another occasion one of my friends went to visit a dojo on the the west coast. The Shihan turned out to be travelling and one of his fifth dans was teaching. He called my friend up to be uke and asked for a tsuki attack. My friend gave him the nice, focused attack he resrves for Aikido people. This arrogant instructor got a sneer on his face and then said in a really insulting manner, "No, give me a REAL punch" The thing was that he had no idea that this particular fellow is one of the senior Tang Soo Do pratitioners in the United States and had trained personally with the head of the style in Korea for many years. So he obliged this haughty fellow with a REAL punch. The guy hadn't even started to move when he got knocked on his duff. My friend then bowed and left the dojo.
This is illustrative of the reason that manners originally developed. You traeted people with respect because you never knew what they knew or how they might respond to a slight. Rudeness of the sort these stupid fellows have shown could have gotten them injured or killed in the old days.
I stay away from people or groups where that type of behavior is considered common. There is simply no rason to have anything to do with such folks. When that person turned his back on you he showed that he wasn't a warrior in any sense. His arrogance left him completely open should you have attacked him. No old time martial artist like the Aikido Founder would ever have made that mistake because they were serious warriors!