Yes, you are correct. They will simply remove you. The scenario imagined where someone lists for an earlier flight, no-shows, then drops in front of the D2s for a later flight with their earlier check-in time is in the imagination of the people complaining about it. The only way this might happen is if you run up to the gate before the agents leave but after the flight closes and tell a good story, not exactly a no-show.

Where it is an inconvenience for others is in planning around the first flight, since they may assume the jumpseat is not available and try a different flight with a similar departure time that is otherwise a worse chance, so as a courtesy it is best to knock out your unneeded listings when you get on.