The only issue I see with this scheme is that it stops working in a post-quantum scenario where ECDSA keys are deactivated. However, if you keep the seed private (and safe for however many decades) it could probably just downgrade to the “secret private key” solution (assuming something like this is implemented).
Ideally I think multi-chain deployments should be provided as a native feature of the chain, but this is a great solution as long as we don’t have that.