Uhmm... and noooo... this forum engine doesn't rock

I know countless more forum much more evolved than this one where you have a gazillion more options and yes, you can ignore people's posts/pm's on those.
As far as the confusion, I pretty much thought he was receiving Pm's here he didn't want and didn't know if there was a trick to block them. The answer for the in-game blocking was already been given, keep in mind though that, once you block whispers, you block all whispers so you will forget about that idea fast.
They do not set blocks in-game because people would simply block the annoying and useless globals (being that 98% of them are total useless spam). In my opinion, just accept the moron which will eventually use his brain and move on.