Okay CCP, you have some trollhards with a serious hardon for mucking up your forums.

You need some tools...

1) Something that (silently) alerts a mod when someone posts the same thing in many threads.
2) Something that (silently) alerts a mod when someone gets a lot of reports from known/trusted forumites.
3) A mod tool that allows silent erasure (set a flag or archive, allowing appeal) of all of a persons posts (past and future).
4) An ability to ban all the alts on an account, perhaps activated when erasure is performed.

Simply locking a thread is not going to do the job... as another can and will be started. As all of these actions are simply database activity it would take very little effort to throw together some utilities.

I'm not generally a fan of IP bans but if they are temporary in nature, perhaps 24 hours, they might not cause too much harm. However, trollhards can find ways around them if they are motivated.

If you want to get extremely serious you can set up some policies and hire some part time folks a low rates to give you 24x7 coverage. And, of course, you'll have to be ready for continued crying as people seem to think they own the internet -- though this is a corporate offering and they are annoying people who are attempting to enjoy your efforts.