Sensible answer is that kids are already studying maths to age 18, they just don't know it because the maths needs are tailored specifically to the course.
So hairdressers need maths training in ratios to mix hair dye. Mechanics need to learn about things like pressure. Neither needs to know quadratic equations, however, someone doing a computer science course might do depending on what they are studying. Someone studying humanities might learn statistics from studying data that they've researched.
The maths they are taught is the beginning of their specialisation within their interests. An arbitrary qualification on top of this is pointless and likely to have the opposite effect- it will turn kids off learning.
He'd do better to create an robust employability and life skills course- things like how to present something at a meeting, how to use spreadsheets and PowerPoint or whatever, basic employment law, how not to piss your boss off, how to make a decent cuppa for your team... Whatever.