Before blogs, before personal web pages, many of us began using email discussion lists to communicate with others. Some of these lists were public, open, and unmoderated, others were closed, edited, etc. Some allowed commercial plugs, personal attacks, sharing of copyrighted information, off-topic discussions, etc.... while others controlled these things. Each list developed its own cultures and communities, and served different purposes. I have managed dozens of listserves, and it is sometimes a thankless and difficult job.
I never thought I would need to moderate a list, and certainly never wanted to, but eventually found it necessary to do so on some lists. I have tried to avoid having rigid rules or policies for doing this, because I don't enjoy spending time making them up, or arguing over the enforcement of them.
It is inevitable that the Huffingpost will struggle with issues about who has the freedom to post here, and what type of content crosses the line. If you deny there will be limits, then you will find in unexpected ways, problems you hadn't considered, including of course legal liability for things like libel, but also cases where you become uncomfortable with the quality, tone, or ethical nature of information someone is publishing.
Transparency about how much freedom one has can be a good thing, because it eliminates the need for extended debates over the right of a publisher (listserve owner, etc), to exercise any editorial control, and it givens the people who blog a heads-up, that there might be limits.
I'm not big on complicated rules, because it is pretty hard to know which rules make sense, and even worse to be expected to enforce them all. But something on procedures can make sense. My suggestions are as follows:
1.If the editors are unhappy with someone's use of the Huffpo blog space, they communicate directly with the writer, and let them know what's up. For most people, that is sufficient. I sometime write people offline who want to post off-topic messages on email listserves, and explain why I think their post is inappropriate (The most common problem: topics that are not related to the list subject matter).
2.If someone won't accept the editor's limits, they are no longer welcome to blog in the space. This kind of thing doesn't have to happen very often, but it is remarkable if it never happens. I ran a list once where one person wanted to post messages endlessly claiming that any effort to promote GPL licenses on software would lead to the elimination of all paid employment in the software sector. This was a smart and very interesting person whose other contributions to the discussions were really great.... but eventually his obsession with this topic was just driving the list into the ground, and he was (quite transparently) removed from the list.
3.If a person gets removed from the blog space, it might be a good idea to give them a chance to explain their side of the story in an exit blog, if they want to call attention to what happened. People can take sides, complain, etc., and life can go on.
None of these comments go to the merits of Peter Rost being part of the Huffpo blog space. Some people were fans of his blog, others probably were not. If I ran the Huffington Post it wouldn't be the Huffington Post. I just think that at the end of the day, it's better to accept that editors exist at Huffpo, and they have some power.