Just goes to show how far the BSV shills can go to try and spread the lies. If Craig had the private Keys to the Bitcoin addresses, Why wouldn't he sign directly from about 5 of them. It doesn't one to have knowledge of Rocket science to do so. As pointed out by odolvlobo, someone already signed a message with pubkeys of the early BTC address using the same procedure. Don't just religiously believe anything you see on the internet.
You ae right. Now, if Craig Wright is the rightful owner of that wallet where a great value of Bitcoin can be found, the best thing to do is to use the private keys and move that Bitcoin thereon to another wallet and maybe even sell some millions to a centralized exchange like Binance and then have everything documented via video. Unfortunately, Craig Wright has proven himself time and time again to be not right but wrong. I don't understand why there remains to be people who are following him and taking his words and actions to be worthy like a crypto leader.