Anti-Splog doesn't protect BuddyPress registration on a subsite

I've setup a site for a client. A subsite with domain mapping and BuddyPress activated for that site only.

After installing I started getting a lot of spam signups and narrowed it down to the registration page on the BuddyPress site.

I don't want to network activate BuddyPress.

So my question...

Does anti-splog and spam protection only work for Network enabled BuddyPress?