There is very little debate legally speaking: If taken to court, he could argue two ways:
1. Entrapment since the officer tailed him before 12:00, didn't know how far away he lived, and because the presence of a police vehicle could have caused the driver to drive more slowly, more carefully, etc.
2. Legislative intent would be more difficult to argue since it usually only applies to vague wording, but since it is clear that intent of the legislator was to prevent people from driving out and about after 12:00, he could argue that since the drive was short, he was driving home, and it was reasonably possible for him to be home before 12:00, he did not actually violate the intent of the law, but simply its wording.
Morally speaking, there are A LOT more arguments:
1. The punishment does not fit the crime.
2. Since the officer was tailing him before 12:00 and he stopped him at his own home, the officers motives are questionable (Was he in a bad mood? Was he tailing the wrong person and simply trying to cover it up?).
3. By wasting his time tailing a kid for a minor violation, he could have let drunk drivers, speeders, and criminals free on the road, endangering other drivers, especially since it was this late a night.
4. In the end, he is being punished for a technicality and for a wrong action. The reason have the distinction between different degrees of murder and manslaughter is because judging someone on technicality is not morally acceptable.
5. The purpose of the law is to keep people safe, and to enforce moral conduct. The purpose of enforcing the law is to keep people safe, prevent people from committing crimes, and to punish wrong doers. Did your neighbor endanger himself or others significantly by being 180 seconds longer on the road than he should have been? No. Does punishing him for doing it prevent him or others from doing it again? No, because his punishment is hardly public and most people don't expect such a law to be enforced so strictly, anyway. Is the police officer punishing a wrong-doer? Not really, for reasons already listed.
Sorry for the TL;DR, but this is all I have to say about this.
P.S. The inaccurate watch thing someone pointed out also makes a good argument.