You are using real logic, you need to use fantasy space retcon logic.
On open space ports, ships suck the atmosphere back in to not lose air using a gravity generator, which would cause the cape to blow towards the ship. Expect this to be a small plot point in “The Mandolorian and Grogu.”
but the air would be leaving the ship, blowing his cape in front of him, not behind
You are using real logic, you need to use fantasy space retcon logic.
On open space ports, ships suck the atmosphere back in to not lose air using a gravity generator, which would cause the cape to blow towards the ship. Expect this to be a small plot point in “The Mandolorian and Grogu.”