About salt in soup

A late three star wrote:
"You should salt soups, stocks, broths at the beginning of cooking, and not in the end, because they would have an acrid flavour".
But before discussing this question, let's observe that the English word "soup" is wrong, because a soup is indeed a loaf of bread, on which a broth, a stock or a potage was added.
Let's also add that salty, acrid and bitter are not the same. Salty is a taste, as bitter, but acrid is probably due to the trigeminal nerve, a sensorial system for pungencies and freshnesses.
How could salt add acridity? Before looking for theoretical explanations, let's begin by checking facts, establishing them... because too frequently, what was said in kitchens or written in culinary books was wrong.
To your pans!
(and don't hesitate sending the results to icmg@agroparistech.fr)