Warning other users about abusive griefers by picture from 3rd party sites

Is it a violation of Community Standards to warn other users about abusive griefers?

Although I was warned that the user was bad news by so many people, I was nice and friended the user. Big mistake as he tried to ruin both me and my partners Second Life and some of our Real Life by going to third party sites with many fake accounts to defame the work done by others. He is a member of Primfeed but this platform doesn't give him (I think it's a him) the opportunity to wreck his havoc yet. He's attacked many people, especially photo and moving image artists both in world and third party sites like Naughty Machinima. He has many usernames. I would like to post an PSA to others with the usernames and picture of his Naughty Machinima sites. He's been reported to both Naughty Machinima and SL. Can I do this without violating community standards. I would not use his SL username or his Primfeed username.