Can anyone explain why ins. will not cover tests for mycotoxins nor cover dr’s who will help?

No one here is going to know anything close to the answer since this is a global forum (mostly English language countries like the US, Canada, the UK, and Australia) but with notable smaller memberships from many other countries as well.

There's going to be a super wide range of local, regional, state and country laws that could cover this restriction/medical censorship (?) you might be addressing. For all we know, there isn't a case of restriction/medical censorship and you're misinterpreting the anecdotal evidence that surrounds your question.