I think the way Roger sees it is that if he stays fit and on top of his game, noone is going to take away his #1 ranking. Therefore he won't play additional tournaments. Therefore he'll still drop out of Paris if he gets to back-to-back finals in Madrid and Basel. Therefore he might still put in a lacklustre effort in Cincy, if he wins Canada.
He's behind in the race. Before he starts thinking like that, he has to cover the gap in the race.