Basillimus,
This is nothing new. There are people who love attention, and will take it anyone they can get it.
In the first place, you should be aware that the moderators frown on people naming wreckers on this forum. That's just the way it is.
In the second place, if you aren't already aware of this, you can use
the key combination of Ctrl & Shift ( correct me if I'm wrong) to view a racers registered name. You have to have the names pop up in the lower right side of the screen to do this.
Anyone can enter any name they want while racing, but this key combo will display their actual registered name.
Use this to determine who it is, and then either work with everyone online to ban him, or perferably, play on a server in which you or someone you know has administrative rights, in which case you can ban him directly.
There are a lot of idiots in the world, but there are also a lot of great people. It's the same on line as it is elsewhere. Keep trying different servers and I'm sure you'll find better company.
P.S. The one thing that keeps this types hanging around is seeing other people get angry. If you curse them and complain about them, they'll stay all night - a WONDERFUL administrative tool is " /spectate racername"
Use this and you can send him to spectate mode everytime he tries to join the race.