I dont see that talk going very well. lol. I do see my Sensei wanting to transmit his teaching of his teacher purely to his students. But there is so much out there, isnt there much more to learn than this senior Shihan's style? Its not as if I am refusing to learn his style but I would like to learn more from others as much as possible.
Don't talk. Listen. Ask his reasons why for not going outside the org then just listen for a clear definitive reasons. The "talk" won't go well if you turn it into a discussion.