The OP sounds like he should find some other support group, this is a community of smart people that will quite happily - and quite rightly - rip any pointless idea apart.
If you're going to editorialize and discount any comments/votes you consider not aligned with boosting anyone's self esteem, or what you consider negative you will create an artificial community - one that is the website equivalent of the old boys network, where the old timers consider themselves superior to the newcomers. Negative comments can be as useful as all the back patting attaboys.
If you really want to do this, the simplest solution is one I am sure you're aware of. Pick a few dozen people you 'like' (their voting habits) to train a Bayesian classifier, then you can weight those those that don't fall in-line with the way you'd like to see you community behave.
Can't we all just act like adults and learn to deal with the negative comments - possibly even learn from the? Do we really need to protected from snarky comments?
This reminds me of a comment thread I saw earlier about people getting bent out of shape by cell phone usage in restaurants! I find lots of things are annoying, loud trucks/buses, cyclists that ignore road signs, rude people etc etc, but I am not going to complain and try to stop buses or give discounts to people who drive to discourage cycling. People need to start learning to cope with the real world and not expecting 'the system' to protect us from ourselves. It's embarrassing to be part of a community that needs voting bias that only encourages positive comments.