So he looks litter trained based on the box, so my “guess” is it’s to help keep any related stains to this carpet, same you don’t wanna put you litter box on a carpet for a cat, also if all his toys/food are on the rug, he’ll probably stay on the rug most of the time.
Just a guess though.
I was going to say “Oh you can potty train any mammal!”
Then I remembered Pandas exist… sooo I’ll just say “Most mammals have had examples of them being potty trained”