Earlier quoted context omitted.
If you were to eat lets say a pound of salt (probably lethal). You probably would have to be rushed to the ER. Your body can only process things so fast and deal with changes so quickly. Obviously, a person would not eat a pound of salt in one sitting. So you body can not dump any excess salt. It can dump excess to a point.
You argument is pointless. Nobody would voluntarily consume that much salt. The same as nobody will drink sea water unless desperate. Once past the point of satiation you would have no desire for more. Hypernatremia will still be a long way off in normal healthy people.
The respondent's point was that there is a threshold at which the amount of salt ingested is too much for what the body can handle.
Obviously a pound is an unrealistic extreme, but it illustrates the point: there is a threshold.
More realistically, it would not be unusual for somebody to have a daily salt intake that is a little over the threshold of what the kidneys can easily handle, and bit by bit, harm can develop, just as is the case with too much sugar, too much fat, too much alcohol, or too much of anything in any organic system.