As often seen, laws don't have to make 100% sense, but they are still the laws.
And there are two distinct areas here that WILL touch you should you be forced to defend yourself and be under a prescription of a substance listed. Think the criminal aspect has been covered but there is also the civil aspect you should anticipate facing. Self defense in the home? Your home owners policy provides a lucrative target for the deceased or injureds attorney. Own a business and are using your company car at the time of the defense? Ditto with regards to a target rich environment for a civil action. And the list does continue.