Cats are weird animals. This is an established fact among anyone who has ever seen one. Fortunately, this behavior does have several explanations! Rest assured, your cat doesn’t hate you for cleaning up after him. He hates you for reasons he refuses to divulge to the press.
One of the most likely explanations is simple curiosity. Cats are inquisitive creatures, and they may not be sure what you’re doing. The act of burying their waste is an instinctual behavior to hide their scent from predators, and seeing you dig up what they so carefully hid might confuse them. Somewhere in the world, a cat is writing to a cat advice column to ask why his human is carelessly revealing their presence to wolves.
Cats also like to watch what their humans are doing, and even try to participate. We’ve all been at our computers and had a cat sprawl across the keyboard to see what the hype is about. This behavior is called mirroring. It’s a sign that your cat wants to be included in whatever strange thing you’re doing, and it’s the cat’s way of spending quality time with you. If your cat is sitting by you or even putting a paw in the litter, he’s simply doing his best to help. It’s not his fault he has no thumbs.
On the other hand, cats are territorial animals. They see your home as their home and everything in it as theirs. The litter box is the only place inside where they can relieve themselves. Seeing you clean it out, the cat wants to supervise you, essentially to ensure you clean it properly and that there will still be a litter box when you’re done. However, territorial behavior can go a bit far. If your cat hisses at you or even attacks you when you clean up after them, this could mean that they feel insecure and unsafe. It’s a good idea to get your cat a second box to use while you clean the first one outside, to give the cat a bit of security that there will always be a usable litter box.
So long as the cat has an adequately sized box and a sense of consistency, he shouldn’t be angry at you for keeping it tidy. Odds are he appreciates it, as cats like to keep their space clean. Plus, he can only bury his waste so deep and appreciates you hiding his location from large predatory birds. Yes, human. Put the dirty litter in a bag to be taken far from this place. Our enemies shall not find us here.