But some people don't like it, and they should have freedom of choice. They pay for the gas, if they want to burn it at a stoplight they should have freedom to do so.

If I was in charge I would say: Keep the existing regulations where it's legally required to be present and legally required to be on by default. Add a regulation that says for new models, it's legally required to have a means of deactivation that can be done by a consumer or mechanic without manufacturer permission or special tools. E.g. a "secret" key combination that you can use to access a hidden menu, but it's not really "secret" -- e.g. it's explained on page 107 in the owner's manual. Just not easy to discover or do by accident.