Are you serious?
You provided a reference-implementation in javascript for the miner and talk about an "attack" if someone chooses different nonces in their miner? Thats ridiculous!
If this is unwanted behavior:
-publish a clear specification or
-don´t accept these nonces
The javascript miner was created to give anyone the opportunity to get our coin, even who can't or doesn't want BrainMining. But we made a big mistake thinking people could play fair.