I suppose I had better add my thoughts.
If someone starts a new forum topic, it is to gain the opinions of all those interested in the subject matter. All opinions are worth reading, even if they are what i call negative input.
Having started a forum, the only thing I would do is try to keep it on track. As we all know, things very often fly off at tangents and the whole thread becomes confused. But as to ownership, I think that belongs to the site, not the instigator of the topic.
If someone enters a post with what appears to be disruptive criticism or abusive, I ignore it.
This forum so far has given a good level of positive feed back.