What I'm saying is that the surface of the Earth is irrelevant in this example. That's not why the pilot is able to make three 90 degree turns and end up in the same place. It has nothing to do with the curvature of the Earth.

In order to perform this maneuver the pilot has to make three 90 degree turns. Only one of those, at most, is going to follow the curvature of the Earth. The other two, which follow nothing physical, are made just the same. After this you can realize that all three turns are made irrespective of physical curvature. The pilot can make this maneuver in any orientation at any height and achieve the same outcome, because they are purposefully flying in arcs to complete the triangle.

A better example would be a ship on the ocean, since the ship is following the curvature of the Earth at all times. Realistically ships probably do not have this amount of precision but hypothetically a vehicle on the surface of a sphere can perform this maneuver with these angles.