It is desirable to use authz to authorize voting and claiming of rewards by a wallet that is less secure than the validator wallet. It is not desirable to authorize that wallet to also change the withdrawal address, because this would allow the lower security wallet to re-direct funds. The claim feature is not enabled without the authorization to change the withdrawal address permission granted.

I'm not sure if this is a feature request, or a bug. It seems like a bug to me, since there's no reason to require one permission in order to enable the other.