In situations like this, it's best to keep calm and move on.
Getting angry and typing in Caps Lock, will just server to make you a laughing stock on the server.
Don't give them the pleasure of it.
If they're going to destroy your stuff and threaten you, they're not worthy of having you on their server.
Find a better place.
He probably made a brickspam house.
That shouldn't matter if he was still building a house.
Even if it's lower quality than others, doesn't mean it should be remove from under the persons feet as they build it.
Usually when someone builds a proper thing, but spammily, they don't know anything otherwise.
I always wait for them to go, then grab a save, then remove it.
I grab the save incase they come back and want to carry on. I remove it so it's not in the way.
Enraging and destroying peoples builds permanently, while they're building it, just because they can't build very well, is not going to let them learn.