Crimes or threats of violence have to be made to get a TRO. Just stay away, don't talk to them, and don't get lured into something. If the ex causes trouble, get witnesses and document it and make a police report showing that he's the victim.
Those can be made up. There have been many a case where the person doing the assaulting makes false claims against the other party, and gets the TRO and assault charges against them!
A judge will err on the side of "caution". They aren't going to consider your firearms rights, if someone claims someone else is harrassing/threatening them, and they have a "witness", you are screwed.
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Going forward, if any interactions need to be made between the party in question and ex, he should keep a log and document the interaction in writing. So these exchanges with the emails and the other parties like the daughter or whoever, you should already be logging.
Any interactions should not be made without the presence of a neutral 3rd party. I would not change driving patterns to satisfy the crazy person's whims. It only encourages more crazy behavior. Just carry out your life as you normally would, and ignore the other party. Any witnesses to intimidation or other behavior should be noted, and perhaps approached and talked to if they're a friendly 3rd party. If a TRO is filed against you, 3rd party statements against the crazy neighbor may be invaluable.
Also try googling the person's name and search for hawaii court documents as well. Generally if people are crazy, they did other crazy shit before, and may have a criminal record. If it came down to action in court, you could (hopefully) point to your spotless record, and compare it with the lunatic's.