Hello Jenth and welcome to ScubaBoard!! I am sorry that I did not see this post earlier. As a NAUI Instructor myself I am embarrassed by the other Instructors lack of willingness to work with you more on resolving this issue. I agree that this seems (if I understand your account of the situation correctly) to be more of a customer service issue than anything else.
I myself prefer to finish any student that I have started. I have been fortunate enough to have been successful thus far. That's the way I was trained when I took by OW class and I enjoyed it. I felt very comfortable with someone who I felt got to know me as a student, was comfortable with my fears and concerns, and who I came to trust would make sure I would complete my course safely. That was a big issue to me at the time as a new diver.
I have never required a student to sign a statement that I am the only one who can complete their training. If your Instructor did so and you were aware of it however, then I can respect his decision, even if I would have behaved differently.
I shy away from suggesting to students that I can get them certified by a certain date. It is dangerous to plan a trip that you need a certification for and not be certified. You run the risk of not completing the certification process for a number of reasons. Some students are just not ready by their target date and I think it is dangerous for an Instructor to sign some one off just to meet a predetermined deadline.
Without having participated in your training it is difficult to know if you are ready for your checkout dives even after 10 pool sessions. I don't know it it is the weather that is keeping your Instructor from taking you on the training dives or if there are other factors involved. I would ask him directly.
It seems as if NAUI has addressed some of your concerns as to how Instructors are allowed to conduct business on a broad scale. With regards to where you go from here, I would discuss with your Instructor what he feels is your readiness to successfully complete your checkout dives. If he feels you are truly ready, then I would attempt to secure a date. If that date is not acceptable to you, then I would explore your option with the other Instructor you mentioned. Hopefully you can get your folder from the original Instructor and simply move on from this experience.
I believe that most Instructors would have handled this situation differently. The NAUI Instructors I know and have worked with are quite flexible. If you have completed your academic/pool sessions and are ready, they'll try and get you into your checkout dives as soon as is mutually agreeable. If there is a disagreement or lack of comfort between a student and Instructor, for whatever reason, they will try to arrange for you to complete your training with another Instructor. At least that is what SHOULD happen IMHO.
While I understand the original Instructors desire to "finish what he started", and I commend him on wanting to see you through to completion, if the lines of communication have broken down such that there is no forward progress on the matter, then it seems time to move on.
I am sorry for this negative experience but I don't believe that his behavior is typical of Instructors in general. I hope you continue diving beyond this experience.