Additionally their are no technical hurdles that prevent other from the same ownership.

That part isn't true, strictly speaking. Blockclain-based systems operate by building blocks on top of each other, in a cryptographically secure fashion. Yes, he bought a bunch of bits, but they are cryptographically secure, on that blockchain, and as long as he takes good care of his bits (and their relation to the smart contract, of course, since he gained control with a smart contract exploit in the first place), they can't be arbitrarily taken away.

Yes, it's all enforced by software, but the same code will make sure that the bits aren't transferred away until a valid transaction appears. Since all nodes have to agree the transaction is valid, be can't just change the validation code himself. Other nodes will reject it. To pull off the heist, he had to work within the bounds of the smart contract to make a valid transaction that did what he wanted to do.

Now, I can't explain why these dumb apes are worth so much, but that's a separate issue. He does actually own the bits now. I would think no one would want to buy them now, though, but the article claims there are already higher bids for the same bits.