010101 one could make the bbcode very specific/unique, almost like a password, so that a regular member wouldn't know how to do it
If the bbcode is rendered in the editor preview, then its name can be found in the javascript source code.
Disabling the bbcode for certain groups could be done in the backend of frontend. In the backend you'd have to hook to the Rendering event and alter the html output by either completely removing it, or removing/adding a class that would disable it.
Or it could be done completely client side, by looking at the post author's groups or a policy on the post payload and using that information to allow opening the modal or not.
