Weight is Ratio

Weight of a person can't be practically zero, but "theoretically" it can be. 0kg = absolute zero; hence weight is ratio.

I agree, that the weight of any object or person cannot be truly equal to zero. Although it might be 0.001kg, there is no true zero. 

Agreed, in the context of weight for living beings, this quantity does not exist, because 0 kg would theoretically represent the absence of mass, but used for ideal or refrenece point.