Hardly sounds definitive. From your link:

"There is a debate about whether the word should be 'less' or 'fewer'," a campaign spokesman said. "Saying 'up to ten items' is easy to understand and avoids any debate."

and

A Tesco spokesman said: "The debate about what is right has been going on for years now, and I still don't think we know if 'less' or 'fewer' is correct."