First off, there is a big difference between legality and being ethical. While there is some overlap, just because something is legal doesn't make it ethcal and visa versa.
Second, I think this cop is a dick for doing that. It was three minutes. Especially if the cop was following him and he didn't break any traffic laws in the process of heading home.
Cops are allowed to follow people if they think that they are likely to break the law, for example, the person may be driving eratically for a little bit, but may straighten out, but the cop follows them for a bit to see if they do anything else strange.
I don't know the whole story here though. I don't know what the laws regarding 16 year old drivers and what times they may and may not drive are. I remember driving home between 12AM and 1AM plenty of times when I was 17, but then, I drive carefully and made sure not to do anything stupid if I saw cops around. I think the cop should have had a bit of a heart, but he was technically enforcing the law.
However, since I see that you live in the US like myself, and keep in mind that laws like this can vary from state to state, so Florida may not have had the curfew. The only curfew I know of regarding driving time is in regards to people with permits.
Anyway, your neighbor can fight the ticket. Bring it to court and have them explain things to the judge. Be prepared for a fight though, because cops hate being wrong. I guess it depends on if you think it's worth that cop possibly having a grudge against you or having your license. I'd fight it, but mostly because the cop needs to learn to have a heart, especially over three minutes. Thirty, I could understand.