Big head mode replay?

So why isn't it possible to save a replay in this mode?
I play it for fun and for the sniper week. Had one Silver leaf player joining my team and dominating 7 people with a Kar98. Literally chaining multikills and getting over 6000 points. Obviously he cheated and use an aimbot. He noscoped since you can differ his walking speed and instahead every enemy. And to add to the misery, no replay could be saved. And as usual, noone F11d him when I voted.