I think that you are overly confident in others' knowledge. The transaction to itself is a clever solution, I won't deny that, but I do expect some will only notice something is wrong if their funds are missing.
On the other hand, I also expect most people don't keep duplicates of the paper wallet, maybe not even duplicate of the address for watching its content online. The truth is that the chances of finding the real owner are not great.
I think it depends a lot on whether this is a
seed phrase backup or a
offline paper wallet.
In the former case, the user would absolutely notice the 2 transactions when opening their wallet application for the next time.
In the latter - unless they've set up a watch-only wallet - probably would not notice until far in the future.
Since easternklaas said the following, I'm not sure whether it's been 100% clarified if this is seed phrase backup of potentially someone's hot wallet, or the potentially only copy of a paper wallet.
I have no idea about bitcoin or wallets aside from what I have discovered over last 24hrs,... which has led me here.