I can think of two possible things:
1. Checking the licensing terms on KawaiSprite's submissions, you will usually see these:
"Please contact me if you would like to use this in a project. We can discuss the details."
or
"You may only use this piece for commercial purposes if your work is a web-based game or animation, otherwise you must make specific arrangements with the artist."
It could simply be that KawaiSprite does not want his works to be remixed.
2. It could also be that the remix was too similar to the original, sometimes that can lead to a song being removed.
You said posted a blammed remix and didn't get banned, remember that Newgrounds is manually moderated. It could've just been that a moderator didn't check you submission yet.
But if you really want to confirm and make sure, then yeah, you can probably PM an audio mod and ask.
funnimonke
@ClunkyDot @ClunkyDot and i posted a blammed remix and didn't get banned