What would that achieve? If you're late to the blockchain (or really any other distribution channel, like https://truetimestamp.org/ or something like this) your timestamp is greater than original and you own nothing. I don't really know how selling 2nd place works with NFTs but I assume you only can get it from 1st place owner (he has to sign it with his private key), so the scheme is solid. You cannot change a pixel and claim something.
The only problem I see is how the 1st buyer knows the seller is the artist not some random dude who changed 1 pixel (or even didnt). You actually cannot reliably sell something that has been published before cause everyone and their mom can claim ownership before 1st token.
I guess I'm misunderstanding what value people see in the NFT. If they really are paying for the right to claim the first entry in some blockchain then I guess it works as intended.
The only problem I see is how the 1st buyer knows the seller is the artist not some random dude who changed 1 pixel (or even didnt). You actually cannot reliably sell something that has been published before cause everyone and their mom can claim ownership before 1st token.