I believe since Twin Cities does not have any USAC dates then the rule would apply. Saying that I would imagine it only really affects about 5-7 drivers who are in the running for the overall championship. If a driver like Robert Ballou who is running USAC races but not really in the running for the overall title it would not affect him at all to run there. Remember its only for the drivers trying to win the overall USAC title not those just running for the sprint title(or midget or SC for that matter).