I don't think there is any law in Pakistan against pets especially cats in homes (I don't know if he lives in an apartment and if different laws are applicable).
However if his cats roam freely, steal milk, hens and other edible stuff from the neighbours or make a lot noise, then it may be a little bit problem. But since he loves his cats and people especially kids love their pets some times even more than their siblings and human friends
I personally don't have any pets because I live alone and have to travel frequently.
Bhai cat = bili ... how can he marry a cat?
Bili se tu shaadi jaiz bhi nahin hai I guess.