BuddyPress Theme as opposed to Farm 100 Themes???

I figured I would start a new thread for this one...sorry to be a bother Andrew but I am a bit confused at this point...politicallygrounded.com is using the Nelo theme, BuddyPress is installed, and when I have paid members they will have buddypress access as well....the buddypress themes that are listing out under premium themes when you click the preview they are blank, if you attempt to activate they are blank...if I am giving BuddyPress ability to people that decide to create a blog does that mean they are restricted to only using the buddypress themes for their blogs as well?

Thanks in advance,
Brad