I'm too softhearted; I gave the guy a chance. Thanks for confirming that blocking can be done -- that is not the world's most intuitive procedure! I might not have pursued it without your reassurance.

I didn't want to have to exercise strict comment controls, but I think your choice of screening non-friends may be the way to go. I'm just grumpy that I apparently need to do it -- I'm not that popular!

Now to go find how to do this stuff ....