My question is, "is that so-called correction correct?"

Have a look at what Mark Liberman blogged.

Merriam-Webster's Concise Dictionary of English Usage is one of the best usage books I own. It gives both the prescriptive and descriptive histories and bibliographic citations. Here's the first paragraph of its entry less, fewer:

Quote:
Here is the rule as it is usually encountered: fewer refers to number among things that are counted, and less refers to quantity or amount among things that are measured. This rule is simple enough and easy enough to follow. It has only one fault -- it is not accurate for all usage. If we were to write the rule from the observation of actual usage, it would be the same for fewer: fewer does refer to number among things that are counted. However, it would be different for less: less refers to quantity or amount among things that are measured and to number among things that are counted. Our amended rule describes the actual usage of the past thousand years or so.

Ceci n'est pas un seing.