I'm confused, are you arguing that cellular changes cannot impact a larger organism because they have too many cells?
That doesn't mean that a detergents can't have other effects that are harmful to humans. It just means that I don't think a cell culture experiment proves anything in such a case. A study in animals would be something different.
Therefore, Roundup might or might not be harmful, but the study doesn't tell us much about it.
Right, because we're instructed not to consume detergents. Following this instruction keeps the detergents outside the body.
We are instructed to consume food grown with herbicides such as Roundup, and Roundup is often (if not always) delivered in a sprayed manner with significant aerosolization.