I don't think being able to view members' forum activities has anything to do with privacy. Mostly it's about viewing members activities within the forum.
We aren't taking about showing email addresses or contact info of any kind- unless someone went and entered that info in their profile, in which case they must want it public. And if they didn't they should remove it. None of our forum user-info can be considered private info. At least it shouldn't be- because a forum is a public place.
As far as being legal- it doesn't matter how legal we are, nobody here wants to be giving their home address and contact info out to the world.
I'm actually kind of surprised there even are those options in our profile to put in personal contact info. Wishful thinking for a safer future maybe.