I see you have never had this conversation with a cop. :)
It's an oddity of law, but they still call it "breaking and entering" even if you don't "break" anything.
My guess it was a trespass, not burglary.
Another oddity. They define "burglary" as entering a structure for the purpose of committing an illegal act. Even if you don't steal something, the law still calls it "burglary."
The law can be funny with all it's definitions not meaning what normal people think they mean.
"Assault and Battery" is another one of those. They define "assault" as uttering verbal threats, and "battery" as actually hitting someone.
I would think "Assault" would require hitting to comply with normal English, but the law uses quirky English. Doesn't an "Assailant" hit? Or Stab? Or do some sort of bodily harm?
Actually I have, though more about trespass which I’ve dealt with on occasion. I mentioned “breaking” only because in the absence of theft or intent to commit a felony, forced entry, aka breaking in, would raise a simple trespass to criminal trespass, a felony in most states. My understanding he entered an unoccupied house under construction, presumably through an open door, which is likely just trespass. And you’re right about intent, which would raise this to burglary, but I suspect intent will be hard to prove. All the history won’t matter much, if all they have is a citizens arrest based on maybe simple trespass, which in many states law enforcement won’t bother with by itself, they have a problem with their defense.