This is his personal holding he's talking about, not (Micro)Strategy.

He didn't claim to buy his personal holding using debt.

However, he doesn't know how a hardware wallet works, as Ben Perrin discovered when he offered to show him how a Coldcard worked.

If he doesn't hold any Bitcoin on a hardware wallet, then if he holds any, they are being kept on an exchange, which means his Bitcoin would be publicly available after his death.

This seems unlikely, so we should assume he holds no personal Bitcoin.