Well, if you don't accept their friend request in the first place, you won't have to worry!
And you can block that ID if you find they aren't realy "friendly" so go all out.

I'm just disturbed that they won't allow you to pick and choose which characters I'd like to share. I love my guild and my friends don't get me wrong, but there are times where I'd rather not be disturbed. I just create an alt and start leveling. Later when I hit the 60s or 70s I hit the guild up for an invite, but until then if I'm on that toon I'm in stealth mode. Now, the instant I create another alt, it will be broadcasted to all my friends, and there will be no hiding.

Also there are some people who have co-workers and maybe even bosses that play the game and I'm pretty sure they'd rather not let everybody at work know that they are using a sick day to catch up on alt leveling. The publicly available Armory history is bad enough as it is in privacy invasion.

For me, I'll probably ditch the whole RealID and ignore any RealID friend requests from any and everybody. No offense.