Just going by the OP's account, I would judge that MB was right (or at least not wrong) to let him go.
I have nearly two decades of professional experience as a supervisor in a light factory setting somewhat similar to what is described in the MB factory. My company makes high quality products for the model hobby industry and part of the manufacturing process is painting and printing thousands of units per week. It has happened (3 times on my watch) where we have hired workers who are serious hobbyists themselves and very knowlegable about our products and the products of our competitors. They were all eager to join our company and even looked at it as a dream job. They said they understood the job was mass production and what we needed from them was an ability to learn quickly how to efficiently perform work of relative drudgery with an attention to detail and quality - regardless of how boring the job might be.
None of these people worked out because they all failed to comprehend that we needed efficient worker drones and had no use for slow workers who considered their innovative ideas for product revisions more important than leaning how to efficiently paint and print.
The last one reminded me very much of the OP's story. We worked very hard to patiently explain what we needed and went to great lengths to demonstrate proper techniques and methods but for some reason he just didn't "get it". Never were we rude or unfairly dismissive. Yet he compained to us that we weren't being fair and he just needed time to get up to speed.
The problem was I have personally trained more than a dozen new hires for this job and I can usually tell within the first week or two who will be a valuable worker in the coming months or years and who is never going to be able to meet our standards. Everytime I've tried to train someone who was constantly trying to change things to be more in line with how he would do them at home in his hobbycraft world it has been a failure.
On the other hand, most of the new hires I've trained have done well and stayed with us for years. One has worked his way up through all the production jobs that he is now the company manager and my direct boss.
The bottom line is that there have been millions of production companies, large and small, all around the world and the successful ones pretty much do things the same way. They don't need someone on their basic production line who has grand ideas about reinventing the wheel yet isn't picking up the concept of simple assembly work.
I have nearly two decades of professional experience as a supervisor in a light factory setting somewhat similar to what is described in the MB factory. My company makes high quality products for the model hobby industry and part of the manufacturing process is painting and printing thousands of units per week. It has happened (3 times on my watch) where we have hired workers who are serious hobbyists themselves and very knowlegable about our products and the products of our competitors. They were all eager to join our company and even looked at it as a dream job. They said they understood the job was mass production and what we needed from them was an ability to learn quickly how to efficiently perform work of relative drudgery with an attention to detail and quality - regardless of how boring the job might be.
None of these people worked out because they all failed to comprehend that we needed efficient worker drones and had no use for slow workers who considered their innovative ideas for product revisions more important than leaning how to efficiently paint and print.
The last one reminded me very much of the OP's story. We worked very hard to patiently explain what we needed and went to great lengths to demonstrate proper techniques and methods but for some reason he just didn't "get it". Never were we rude or unfairly dismissive. Yet he compained to us that we weren't being fair and he just needed time to get up to speed.
The problem was I have personally trained more than a dozen new hires for this job and I can usually tell within the first week or two who will be a valuable worker in the coming months or years and who is never going to be able to meet our standards. Everytime I've tried to train someone who was constantly trying to change things to be more in line with how he would do them at home in his hobbycraft world it has been a failure.
On the other hand, most of the new hires I've trained have done well and stayed with us for years. One has worked his way up through all the production jobs that he is now the company manager and my direct boss.
The bottom line is that there have been millions of production companies, large and small, all around the world and the successful ones pretty much do things the same way. They don't need someone on their basic production line who has grand ideas about reinventing the wheel yet isn't picking up the concept of simple assembly work.
At least keep Martin out of that, m'kay!?! 
There is some skill to it though; setting the neck, scalloping braces and scraping the binding. You got to have some precision and a little touch to do that...
