Dangerously sensible
Standing around demanding that people under the age of 18 are forever sober is not a realistic stance, similar to demanding people under the age of 16 do not have sex. Issuing guidelines at least gives people an idea of reasonable limits, just as teaching teenagers about contraception is eminently sensible.
Problem is of course the tabloids will be frothing at the mouth screaming something about the government encouraging toddlers to get off their mash on extacy pipes. Sadly this will probably lead to them backing down and shelving the idea.