Less muscles? Less muscles? I never thought I’d see the day when Cecil would use this sort of fractured grammer.
It wasn’t Cecil who used less instead of fewer; rather, the reader who asked the question used that wording. When replying, Cecil wrote:
Then the webmaster who posted the link on the front page perpetuated the questioner’s phrasing, perhaps to lure grammar pedants into clicking on the link in a futile attempt to catch one of the rare Cecil errors, which all get blamed on lousy copyediting anyway.
My favorite variation on this is something like: “It takes 43 muscles to frown and 17 to smile, but none at all to sit there with a stupid look on your face.” 
I didn’t realize that the question was a quote from the submitter. I assumed it was a summation (created by Cecil or a staff person) of the body of the query.
I’m not really a grammer nazi, but *fewer and less * is a pet peeve with me, along with momentarily (in place of “in a moment”).
I assumed this was the subject line of the email the person sent. Anyway, shouldn’t be blame li’l Ed? He’s the editor, after all.
My favorite variation is this:
“Remember, it takes 42 muscles to frown and only 4 to pull the trigger of a decent sniper rifle.” - Michael Hohensee
Gaudere’s Law strikes again!