I am very much opposed to puppy mills, but this seems like gross government over-reach to me - they are dictating where pet stores can buy their stock of pets, and no doubt restrictions on buying from private breeders will be coming along soon. There are better ways to deal with this issue, but of course direct government control over business is always preferable for liberals.
When politicians dictate what can be bought and sold, it means the first thing bought will be the politicians.
If you are opposed to puppy mills, why the objection? Libertarian as I am, I think it’s a Tragedy of the Commons thing. That being said, the effects of the law won’t be very good. Ninety percent of the dogs in shelters are pit bulls and pit bull mixes. I’ve seen for myself. This law results in an increase of pit bull types in homes. Bad idea.