Right, but who is the multi in the multisig and what happens if they die.

You can be the multi yourself. Choose diverse hardware (ie, not all the same Ledger) and your likelihood of compromise changes significantly in your favor.

Sure, loss of seed material would be catastrophic so have a backup scheme. The point isn’t that you can make it perfect, but there’s laughably risky and imperfect solutions and putting everything on a single key HW device like this is the poster child.