The "protection" that Wang keeps mentioning is often refereed to as a BMS or Battery Management System. What it is essentially is a chip that controls the amount of electric each battery is storing, this is to ensure even discharge/recharge of the battery which results in a longer battery life.
If I am following correctly, Wang has built a BMS into the wGrill so one is not needed on the battery itself. Having two BMS's will be detrimental to your battery since you cannot have two things managing it at the same time without adverse effects.
Think of it like an orchestra with two conductors, it just doesnt work.