It sucks when valuable contributors leave. And like Mos said, you can't really avoid conflicts on sites like this without moderation being instituted. Problem is, once you institute moderation, the site rarely stays like this. The moderators (whether intentionally or not) will always piss someone off when they "side" with one member or the other.
Like I've said a hundred times before on this site and the "last" one, it's just words on screen. You can ignore them just like you ignore pop up ads or side bars. If they're just looking to get a rise out of someone and nobody takes their bait, they'll get hungry and move on to greener pastures. It's just like free speech. We all love it. Until somebody starts saying something that pisses us off. Best you can do is listen to something else while they're talking.