Well, as he says, he already moderates it while he sleeps. But he is considering leaving moderation up all the time. I hope he doesn't do that. Oh, I understand why he is considering it. His blog has currently attracted quite a few trolls. But, as near as I can determine, internet trolls seek to disrupt communications wherever they go. Alex would be handing them a victory.
Now, I have had some trouble with trolls in the past (most notably Norman, but even then Alex has run into more of his personalities.) But I have never had the level of difficulty that Alex has. I think there is a simple reason for this. My blog is just not that popular (*sniff). If you write a popular blog, you're going to have trolls.
I suppose, though, one trick to preventing such a situation is to learn to identify trolls quickly. I have some guidelines.
Someone who uses multiple accounts to post on the same blog is probably a troll, and the more accounts, the more likely. Please note that I am not talking about someone who has one account with each of several servers. That can just be someone who browses blogs on different servers and keeps an account (preferably with the same name, but sometimes it is taken) to comment on various subjects of interest.
Someone who says "all atheists are irrational" (or, for that matter, "all christians are irrational," "all muslims are irrational," or the like) is almost certainly a troll. I do not assume that you are stupid or irrational for disagreeing with me. It only means that you are wrong. (;-P) Very intelligent, very rational people still hold on to some wrong beliefs throughout their lifetime. Gratuitious insults are the way of the troll.
Another identifier is that trolls will often come on to a blog and accuse someone who has been commenting on that blog for quite a while of "following and harrassing them."
I am sure there are other identifying characteristics. But those are the ones that come to my mind right now.