Are you kidding?
Why blocking an old client, when it works well? Noone was ever thinking about blocking old clients, until Vinnie came with his false rumours again, he constantly did badmouth Xolox instead of learning from it. Why would somone likes to block Xolox? Xolox works well and is one of the best clients still. Perhaps you want to give us some facts.
PS: Zeropaid article "Bearshare to Block Xolox? NOT!"
http://www.zeropaid.com/news/article.../01092001b.php