Yes, it takes over 70kg of "mass-energy" (e.g. mass converted to energy in nuclear fission) to remove 1% of all electrons in a person weighing 70 kg. That is no

Yes, it takes over 70kg of "mass-energy" (e.g. mass converted to energy in nuclear fission) to remove 1% of all electrons in a person weighing 70 kg. That is not, in itself, contradictory. Depending on how relativistically inclined you are, this may affect what you consider the weight of the person. But this doesn't really matter for the thought experiment.