Just brainstorming here. You suggest that an anonymous mint could be trusted if it had more bitcoins locked up in a smart contract than in the wallet for its users provided that the users had a way to grab those bitcoins if their funds don't get honored. This requires a lot: Knowledge of outstanding IOUs. Knowledge of funds under reserve. The bond being distributed between many users that often might not have significant balances individually, justifying an on-chain transaction. After all that's why many use a mint. In order to prevent rug-pulls, it does not matter where the funds flow as long as they don't flow to the hacker. By paying out to users, you almost can't prevent the hacker from holding an insane amount of IOUs, diluting all other user's claims. Therefore it's more feasible to just send the bond to a burner address.

Good point. Either each minted coin can hold a claim on the bond, and when that coin is redeemed and renewed by the mint, the mint can expire that contract and issue a new uxto that could be redeemed based on some rugpull oracle; - or - Rather than transferring custody of the actual sats to the mint, the mint is only in charge of the blind signatures and the token itself contains something like a hodl invoice that is reissued upon each reminting.