Then he would have a 'signature chain' fork like a Bitcoin fork. Our rules wouldn't accept their transactions.
And that example above is the initial signature and doesn't need a transaction as mentioned in the 'how it works'
created a 'signature chain' transfer:
1NCLNyKPGjx2GwdRSPB5xqfy58WtGtgNgo is the starting address (first time used in 2022, it is not an old address, just to show that it works)
The owner/holder of 1NCLNyKPGjx2GwdRSPB5xqfy58WtGtgNgo transfers the 'signature chain' to 1M4wDv1tGEt2yPL6FrkM6o19jxV6mdopnP:
1) signs a message (message is the Bitcoin address of the new owner)
-----BEGIN BITCOIN SIGNED MESSAGE-----
1M4wDv1tGEt2yPL6FrkM6o19jxV6mdopnP
-----BEGIN SIGNATURE-----
1NCLNyKPGjx2GwdRSPB5xqfy58WtGtgNgo
H5U5G/qQy2pk5Es6LCFrfzKuA5vFnpq7oBT4/V91jhGRafWg9Bq8A6Au+tPYNE/kdAm07JkcL82QTJ6QlSPr86Y=
-----END BITCOIN SIGNED MESSAGE-----
2) transfers Bitcoin from 1NCLNyKPGjx2GwdRSPB5xqfy58WtGtgNgo to 1M4wDv1tGEt2yPL6FrkM6o19jxV6mdopnP (to the new owner)
txid 167af01dd191b0e2d47f7255a9f440789a0ae7cba92a644f69d2b39e1f120eaf
Block 765905
04/Dec/2022 9:25 PM UTC
output: only 1 legacy address = valid
Now 1M4wDv1tGEt2yPL6FrkM6o19jxV6mdopnP is the owner of this 'signature chain' and tranfers it to 1B2a3bau6T5jHRgzWo4pzRj93fkPNaPZHj:
1) signs a message (message is the Bitcoin address of the new owner)
-----BEGIN BITCOIN SIGNED MESSAGE-----
1B2a3bau6T5jHRgzWo4pzRj93fkPNaPZHj
-----BEGIN SIGNATURE-----
1M4wDv1tGEt2yPL6FrkM6o19jxV6mdopnP
H22/CTmYHFL5SPorqchj44pya7QRVYekvBxiqVslfMJechxQ1hE0tYpRjCxB/77A3tohMuhC1Pafa44wDgqlrWY=
-----END BITCOIN SIGNED MESSAGE-----
2) transfers Bitcoin from 1M4wDv1tGEt2yPL6FrkM6o19jxV6mdopnP to 1B2a3bau6T5jHRgzWo4pzRj93fkPNaPZHj (to the new owner)
txid 12bbc865f8b5259cd0c40a5da954e488e555f746a59d001f225b94ebde73a8c9
Block 765907
04/Dec/2022 9:55 PM UTC
output: only 1 legacy address = valid
Now 1B2a3bau6T5jHRgzWo4pzRj93fkPNaPZHj is the owner of this 'signature chain'
1NCLNyKPGjx2GwdRSPB5xqfy58WtGtgNgo
1M4wDv1tGEt2yPL6FrkM6o19jxV6mdopnP
1B2a3bau6T5jHRgzWo4pzRj93fkPNaPZHj
and can transfer it.
It works

You can't break it. It works.