Why? Why not just select the option to hide his posts? That's what I did.
I don't think banning people is a good idea.
If an anonymous account's only contribution here is innuendo and ad hom, they can watch from a distance. That kind of behavior would have been tolerated for 60 seconds on PhysicsForum or StackOverflow. Banning all the time and lots of people is no good. Banning flagrant trolls is not only good but desirable.