You're misunderstanding what he's saying.
When you're elected into the NONCONSTITUTIONAL BODY calling itself Congress, you are now participating in a system in which YOU MUST BE AN INHABITANT OF THE DISTRICT OF COLUMBIA.
If you ARE AN INHABITANT OF THE DISTRICT OF COLUMBIA, you cannot be an inhabitant of the state you're purporting to represent. Ergo, there's a de facto term limit imposed on themselves by their own machinations. Its just that no one has noticed.