I recently added someone on my friend's list on diablo3, and good god he is not only a total prick to my other friends and constantly bashing them, but he is stalking me! I have blocked him and reported him, but he seems to know when I'm playing diablo because he starts sending me emails confronting me. I've blocked his emails too, but of course you can make unlimited email accounts. I'm also afraid he is pestering my friends on his recent players list too...
I do believe your best bet is to contact Blizzard with this thing. I don't think you can affect the recent player list of others.
Heck, even if it IS possible to affect someone else's recent player list (I'm sure someone will correct me if this is the case), you should still contact Blizzard!