.... In the other arts with which I have been involved in since I stopped regularly teaching and training in aikido, I have been able work with master-level instructors in non-fixed-role resistance training scenarios. The fact that that this training does not exist in aikido makes it a virtually useless art for me at this point given the alternatives I have. It's not that there is nothing more to learn, but just that I don't believe that it is possible right now for me to learn much more of value without engaging in certain types of training that are mostly absent from aikido.
Then don't be involved with Aikido anymore .... period. If you're ahppy training somewhere else and don't like the way Aikidoists train or do seminars, don't go at all!
There are plenty of people who do enjoy those seminars. Feel free to let them have the mat space.