I don't think there is any such thing as a hex controlled by a minor country in the game unless the minor is still neutral.
All minors align to a Major Power, or they are conquered. There are no Tibetan hexes or Liberian hexes. There are Major Power hexes, and neutral hexes. Basically nothing can happen in a neutral hex except resource transportation. And passing the Panama Canal I guess.
That must be the RAC language, which I'd say has a hole in it at the end of the language, and repeats a small problem in RaW:
After the U.S. has closed the Panama canal (see 13.3.2, entry option 33), you can only move naval units between the Gulf of Panama and the Caribbean Sea if:
Its controlling major power of the three Panama Canal hexes is at war with the U.S.A. and lets you; or,
There is no controlling major power of those hexes and the U.S. player lets you.
Canal Open before Option 33, Panama neutral or active and aligned to even neutral USA = any country moves through
Canal Closed by Option 33, Panama neutral = USA decides
Panama active, controlling Major Power @ War with USA, Option 33 not picked = Canal Open to any country including USA (this is a problem case to say the least)
Panama active, controlling Major Power @ War with USA, Option 33 Closes Canal = controlling Major Power choice
Canal Closed by Option 33, Panama active, Controlling Major Power Neutral towards USA = Mexican Stand-Off? No one sails through?
this is because that RAC language when parsed, doesn't include that last case just above, because Panama is always either neutral or the hexes are controlled by a Major Power - which may or may not be at war with the USA, and RAC doesn't answer the last case.
Option 33 would not be picked unless the USA chooses to select it, or the USA is at war with Japan, Germany and Italy, when it is selected automatically
RaW is a tiny bit tighter:
7. After the US has closed the Panama canal (see 13.3.2, entry option 33), you can only move naval units between the Gulf of Panama and the Caribbean Sea if:
ï its controlling major power is at war with the USA and lets you; or, if none,
ï the US player lets you.
which allows for the idea that there is a controlling Major Power not at war with the USA, giving the USA the decision even if Panama has a controlling MP not @ war with USA
RaW also does not consider the case that Panama could have a controlling Major Power before Option 33 is selected. Or it does consider it, and the Canal Zone becomes quite a strange place indeed, with John McCain's father keeping it open for anyone and everyone, no matter who is in charge in Panama City
So in Zartacia's game here I would imagine Germany is making every Panama Canal movement decision because it is at war with the USA.
The test would be simple -
Allies DOW Panama but not the Axis
controlling Major Power does not DOW USA
and see how the ships move. I expect MWiF will get it right, even if RAC has that tiny flaw and neither address the idea that Option 33 hasn't been selected.
So you could test it again with and without Option 33.