Yes, it is against the site rules to give positive comments with low ratings.

There is a thread about this type of behaviour already.  You can see that others are concerned about this too!

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2729572

You did the right thing in notifying the Moderators about it. However, they will probably tell you that there was no need to post the complaint that you sent to them,  in the forums and I suspect that they will probably lock this thread.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi