I'm not sure it will be good. but for me, it would make me even dizzier with piles of wallets and keys.
the risk is not in the hack, but in the error in ourselves.
After all, it doesn't cost to download a wallet and generate a key phrase. If that is the best way that he thinks he would be safe from scammers, it is good for him. But his method will be possible and not difficult if he only has one type of coin for example only Bitcoin in his wallet.
However, it's somehow tedious, I cannot consider to do that instead I will rather be careful about where to connect my wallet addresses and ensure I did not reuse a particular address.