I live in Ohio also, there is no statewide Curfew Statute. The 1-5 time frame you reference pertains to drivers and probationary driver licenses, etc.From my understanding, curfew for teenagers 17yrs or older in Ohio is 1am-5am but apparently our city has their own ordinance and curfew starts at 11pm. I explained this to the officer that I had given him permission because I was not aware that our city has its own law. A ticket was issued anyhow.
Municipality's can enact their own curfew ordinances pursuant to the Police Power granted by the Ohio Constitution Article 18: Section 3: commonly known as "Home Rule".
Obviously, the officer did not believe his "lawful activity" defense. It seems he could have waited and contacted you then or later, as it is a Minor Misdemeanor and has 6 months to initiate a prosecution. He of course will need you as a witness to verify he had permission. Once that is established, there should be no reason for the Court to find him guilty.

