This is hindsight bias. Knowing math helps cure you of the affliction of hindsight bias. The fact is, you don't know what career a person will end up choosing, and math is important (as is art, music, philosophy, chemistry, physics) in a subset of them. Therefore, if you want ANYONE to be able to do the math for you later on, you need to expose everyone to it to find the future mathematicians.
Not everyone grows up to be a writer, but we all read Shakespeare. Is that a waste of time? Only in hindsight.
And maybe, just maybe, this guy isn't all that smart and the test is valid. But of course, the article doesn't address that, as it's more interesting to write about anecdotal evidence and drama for the innumerate audience.