I really think you didn’t read my full comment, because I explained the problem with this exact scenario.
First, in your hoolahoop example both sides of the hoop are moving with the same velocity (this is essentially option 3 I described). But the entire thought experiment is “what if the two sides didn’t move with the same velocity”
If you’ve played the game, you know that you don’t instantly teleport when you touch the portal, you can be half in the portal. This means that when something enters the portal, it is deposited on the surface of the other portal. So as your arm enters the portal, your hand needs to move out of the way to make space for your arm.
If your hand doesn’t move out of the way to make room for your arm (it is still because it has the same momentum that it had when it entered) then your arm will materialize in the same space as your hand. Now scale that down to the atomic level, if the atoms of your fingertips don’t move for the next atoms, everything will be deposited in a 1 atom thick film.
If your hand does move out of the way fast enough to make room for your arm, then it is moving at the same speed that the train was moving. Your momentum from that speed would fling you into the air.
In no scenario do you just pop out intact but motionless.