Ok, quicker than expected - version 1.1 has been released.
Version 1.1 is fundamentally different from Version 1.0 in the way it works. The usergroup options are now no-longer "Can use BBCode". They are now "Disallow use of BBCode".
By default, all usergroup options are set to "No", which means everyone will be able to use BBCode as normal. To block a certain usergroup from using BBCode in posts, sigs or PMs, edit that usergorup and set "Disallow BBCode in ..." to "Yes".
If you notice any problems, let me know - it appears to be working ok for me on 3.5.1