This is my opinion:

Tests can only and should only be used to support a clinical diagnosis.
It sounds that one physician thought your symptoms could fit myasthenia (and sent those labs) and another thought they couldn't. There is no way for me to know which of them is right.
From reading your other post it seems that you don't have a "classical" disease that nicely fits into a known "box".
I think that the right thing for you to do is not bother yourself with those or any other tests, but find a neurologist you feel you can trust, who will eventually figure it out by putting together all the pieces of the puzzle- the clinical picture, the results of various tests, the response to treatment etc. Not one that carves order by leaving the disorderly parts out.

The name of your illness is much less important than finding the proper treatment that will help you regain as much as possible of your normal life.

My illness initially had no name and I was given inadequate treatment.(mostly symptomatic treatment and more aggressive treatment only when I had potentially dangerous symptoms).
It then had a name and I was given even less adequate treatment. (the treatment that "should" work in patients with an illness with that name, but led to deterioration in my case).
Only now does it have a name and I am given proper treatment. (less commonly used treatment that can work in patients with an illness with that name, but is more commonly used for a very different illness, which I clearly do not have).

As a physician, I see in my clinic healthy people with abnormal test results. I also see very ill people with completely normal test results. I tell the former to keep on enjoying their life, and I take care of the latter.

Some patients respond to commonly used treatments and some don't.

If you trust your neurologist, go with what he says, and let him gradually find with you, the best management approach. If you don't trust him, find another one.