Having played less than 15 tournaments the entire year and taken frequent month-long breaks, fatigue is the last thing Federer should be complaining about. He has the option to withdraw from Paris if he so desires, as he has already played 8 out of the 9 required Masters events and if he doesn't, then he probably figures it won't affect his TMC preparation. It's not as if any of his matches are particularly energy-draining.