Good morning Jeremy,
>If a sender needs to know the recipient can remove the covenant before spending, they may request a signature of an challenge string from the recipients
The recipients can always choose to destroy the privkey after providing the above signature.
Indeed, the recipients can always insist on not cooperating to sign using the taproot branch and thus force spending via the `OP_CHECKOUTPUTSHASHVERIFY`.
Regards,
ZmnSCPxj