Biggles,
No, it doesn't say anything about order of accuracy in an operating rule, that's all buried away in certification rules.
There is no provision for any defense.,
The defense is the defense available for any strict liability offense. See the Criminal Code.
Of course, something like this should never be a strict liability offense. It should be up to the prosecution to prove that there was intent to run below the fixed final reserve.
Say, planning totally inadequate operational reserves in the first place, or deliberately continuing when it should have been clear from the howgoesit that the fixed final reserve would be breached.
It doesn't care if the actual winds are worst than forecast.,
Quite correct, that's what variable reserves are for, and a howgoesit, and if you are going to run short, divert and get some more motion lotion.
It doesn't care it you have a slow fuel-leak.,
If you can prove that, it would be a defense.
It doesn't care if you get held by ATC because of problems due Wx or worst-than-usual congestion.
Correct again, that's what you carry ATC holding fuel for. If you get caught out by unexpected ATC delays, divert or declare an emergency.
Here is where the Yanks have a good way of handling the matter, declaring a fuel state ( don't remember the correct words, off hand) without having to declare a full-on Mayday.
It doesn't care that you've had to do bigger diversions due to worst-than-forecast Wx or conditions.
Spot on again, if your pre-flight planning and resultant fuel load proves to be not enough, as the weather and ATC diversions and delays develop, commonly one resulting in the other, same required solution.
Hardly even what you would call a command decision, really, just plain common sense, but in Australia we seem to need to regulate to require common sense.
The fixed final reserve, as a concept, is ezzzactly what it says it is.
Tootle pip!!
PS: One of the few ramp checks I have ever had, back in the days of "the good old DCA", involved checking my fuel remaining. It was a Cessna 205. I demanded that the only way to determine the fuel remaining, was to fill the tanks, at DCA expense, and see how much it took
The inspector took the bait, I was well inside the then 45m reserve, and was left with a free load of fuel for the final 90 minute leg of the trip. I haven't had too many wins like that one, over the years.