There are two reasons why this infection is treated to a nuke and pave. The first is the problem with removing the infection from all files without causing system instability. The second is the backdoor that this nasty attempts to create.
Somebody in a remote location could access a PC as if they were sat in front of it, and so there is no way of knowing how many malicious files may have been dropped on the hard drive, legitimate files patched or replaced, and if security settings have been lowered to make the PC easier to infect in the future.
The difficulty in guaranteeing a clean PC makes a reformat and reinstall the quickest and safest option in the long run, particularly if there is sensitive data on a system.