I've been working with support on this issue with the latest 10.2 MP5 client. It is a known issue to them that you cannot disable SSO on this version. There is no fix from them yet.
The article you linked and the related registry locations and settings do not work. I'll update you guys once Symantec support sends me back a fix so far it's been more than a month without a fix. I'm currently using MP4 but this version has it's fair share of bugs as well....