The reason this wouldn't work is that users are sometimes banned because they cheated in order to obtain their pets. There's a reason those accounts are frozen. Also, if you took a year or two long hiatus because of certain reasons, and then you came back to find all your pets missing, would you be very happy? Many users work hard for their pets, and I know I'd be furious if for some reason I left the sight for a while and came back to find that a user obtained pets that were very special to me, that took me ages to complete the goal of obtaining them, for free. You might as well sign up with a new account.

I guarantee that if you set a goal to obtain something you want, and you keep at it, you'll complete it sooner or later. But there's not much anyone can do for the pets belonging on frozen accounts.

Some people might leave rather abruptly, and might not have time to send all their pets to Pat. Besides, that would be a lot of work for Pat and staff, they have other things they need to work on. Pulling pets out of frozen users' showrooms doesn't happen all that often, and it's already quite a time consuming task.

Items/pets/TU from banned accounts will never be distributed back into the community. Most of these things were gained by cheating, and need to just go away, not continue to circulate. 

This is also in the "Topics not open for debate" sticky at the top of this forum.

Banned/Inactive accounts
Items, pets, tu, or anything else will not be put back into circulation from these accounts.