Probably that at the moment. His average society level is 44, which means most of his planets are probably too young to worry about. That still leaves him with an awful lot of places to deal with, but that can be cut down by only worrying about planets on the outer edges of his empire and only sending up big fleets from the inside whenever he needs them.
I guess when you have so many planets, you just let them all grow and not to worry. It would take a massive fleet to capture even half of his stars. Even then, he would still have enough planets to build fleets to fight you off.
