I've read this about 5 times and I can't make sense of it.
his reason to vote "positive" in the first place.
What positive vote? Aren't we talking about downvotes?
Why would you then downvote?
Because a post is overvalued. It's the only valid reason for upvoting as well (a post is undervalued).
Flagging should be separate and only be used to censor spam or dishonest content.
I agree. flagging should only be used to censor spam and dishonest content. But its quite clearly not that way on here at the moment. It's being used to censor even when others quite clearly have upvoted a post of interest.