How come Nadal plays the ATP Queen's already and Federer doesn't?

Federer feels the most comfortable on grass so he doesn't need to go to the warm up tournament then I think the lost he wants to go home and maybe spend time with his family. Grass is Federer's best surface and has had the most successful on it where Nadal has to tweak his game to work on grass so he needs to prepare because he plays different on clay then he does on grass. It's a short amount of time but he can get a couple of matches at Queens to get use to how the grass feels so when he shows up at Wimbledon he can have so confident on the grass.