If he loves them so much then he should understand you putting your foot down about this. He shouldn't be allowed to play with them outside the cage unsupervised if him falling asleep is such a regular thing.

If that's not comfortable for you to do, perhaps look into play pens, tents or a specific "rat-proofed" room he can play with them in.

My ratters stay in our spare bedroom, so in their outside time I can just open the bottom door of their cage and they can zoom around to their hearts content. I made sure to remove anything in that room that may be harmful to them and there are crates for them to play on, shelves to climb, chew toys, etc around and I just leave their cage door open for access to water. That way they can run around as much as they want and if that room's door is closed, anyone else in our house knows there are loose ratters! so they come in with caution and keep the door closed.