It's actually a worthy idea, but the timing is wrong.
We did similar things with Melbourne Victory years ago when they tried to shunt those of us who sang behind goals.
People power works, but you need a large passionate group for others to rally around or lead the way, and TBH I don't think you can make the same sort of mark for AFL unless you got say the cheer squad to do it.
When the north end was empty and no singing at the game until say the 70th minute or even post game that means you are seen and heard. AFL has supporters all over the ground. Would need both members areas and cheer squad empty, then full after quarter time to make a ripple.