Technically this is the kind of option (along with player count, what maps are playable, if players have the same map, etc.) decided by gurus (those who play the game a lot) near the end of each arena season. And as it is a variant in the available on BGA, I imagine they could decide to implement it. But for this (and every arena season thus far) they have decided not to use the peaceful variant. So I find it unlikely they will change it, not that my opinion holds any weight.