I don't know for sure but I suspect you are correct. A statute requiring the courts to defer to an administrative agency would likely be ignored stuck down as a violation of separation of powers.
As I mentioned before, I'm not a lawyer but I am an Enrolled Agent, which licenses me to represent clients to the IRS on the same basis as an Attorney right up to the Tax Court door.
From this background I know of many cases in which the Tax Court has overruled the opinions of the IRS counsel as to what the Tax Code really means. Taxpayers are treated way better than pilots by this system, which is why from my non-lawyer view the FAA/NTSB administrative law system looks like it was imported from North Korea.
Which is why disregarding FAA Counsel letters is risky and shouldn't be done lightly.
And I also mentioned the super high profile case (in the tax world anyway) of
Loving V IRS in which Federal district and appeals courts absolutely slammed the door on a major IRS initiative because the black letter law written by Congress never gave the IRS the authority to implement the regulations they published. Because neither 'letters' or even official agency regulations are themselves 'laws'.
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MAKG provides a rational reason to consider asking for an FAA legal interpretation:
In a nutshell, to prevent sanctions for doing something you didn't realize (or didn't want to realize) was not allowed, because something in the regulations is ambiguous.
OK, that's sounds reasonable. Just realize that you may open Pandora's box concerning the 'something' that you're not sure about doing. If you consult an aviation attorney, and he helps you craft the question in such a way that the answer will hopefully be narrowly construed to affect only the unique aspects of your situation, then fine, go ahead and ask.
If, on the other, you just want to explore some corner of the rules/laws/regulations/letters/dictates etc out of general curiosity,
PLEASE DON'T ASK IN WRITING.
Asking your question to an FAA lawyer in writing may generate an answer that adds new restrictions on pilots, restrictions that are unvetted by anybody outside the FAA.
That's a bad thing!