I dont' agree with this
Rating reviews is a subjective task based on subjective reviews; IE people giving opinions about opinions. ("Yo Dawg! I heard you like opinions, so I decided to give you an opinion on people giving opinions about opinions!")
Since it's all subjective, you can't just arbitrarily dictate what is "Abusive" and what isn't. The things I consider "abusive" reviews are if someone puts completely worthless information in their review, like gobbledygook or gibberish that has nothing to do with the flash. However, that is relative based on the flash in question. EG: the string of dashes and numbers ...that's a review for Evil-Dog's Punk-o-matic. Someone liked the game, and decided to share their own mix. Nothing wrong with that in my opinion. At least they PLAYED the game, and seemed to enjoy it. No better compliment than to show the artist you enjoyed their work.
Now if someone blasts the flash as being shite, then so be it...it's their opinion. If nobody agrees with the review, they'll down-vote it. If enough folks think it's unwarranted, they'll delete the review. But in some cases, a flash deserves it and it'll get up-voted. In some cases, a flash is complete crap, and you don't want to waste the time bitching about it. So, it's nice seeing someone doing the bitching for you, and you can just up-vote them.
Can the reviews be completely cut-throat at times? Sure. And on the internet, people are prone to extremes of emotion...things are either "ZOMG! TEH BEST!" or "ZOMG! DIS SUXORZ!" But when you look at NewGrounds avg audience demographic (tween/teen hormone-laden males), it's to be expected. Trying to organize and dictate how reviews should be written and rated by folks like this is like trying to herd cats through a meat grinder while being on fire and having your nuts slammed in a door.