Well, that's the question at hand. If startPos = [21, 12] and endPos = [21, 12], does the ship actually move? It may, it may not. Stationary may be a different case, it may not.
You're declaring that it does, but don't seem to have anything to actually base that on as far as rules/rulings/evidence goes. And that's kind of the problem I'm having here - you're making a lot of declarations for what is, and why stationary has the FAQ entry it does, and what does and doesn't count as movement... but you're providing absolutely no evidence, and every time you try and explain it you show, yet again, that you don't actually understand how movement works in X-wing.
But what you are trying to suggest is that since the ship ended back where it started, it didn't move at all and the 'previous touchings' were not break. That's what is wrong... And precisely there lies the paradox... if the ship didn't move at all, how it overlapped what it had in front?
The ship did overlap to initiate the "touching" state. That state lasts until one ship or the other moves so that they're no longer physically touching. I pointed that out several posts back.
We know that for stationary maneuvers, if you overlap (and therefore are touching) that touching state can last multiple turns. You don't have to overlap this turn in order for it to be maintained. If two shuttles hit each other, and then have Yorr pulling their stress as they do stationary moves, they could stay touching for the rest of the game based on that one overlap.
So the question is whether overlapping and ending back at your same position counts as moving. Logically, I don't believe it does - if there is no change in the game state, you didn't actually move anywhere, there is no time - not even an instant - when your ship is in any position that is not touching the one in front of it. The condition to reset the "touching" state is never met.
I believe this is why there's a difference in the "start touching, same maneuver, still touching" case. The lead ship executes first, completes its maneuver, and there is now a time when they're not touching. They've moved away. In a case of stationary move - selected or otherwise - there is no such point in time when they're not physically touching. So, they're still touching.