http://www.express.co.uk/life-style/health/630515/beer-shock-mens-safe-drink-limit-slashed-three-halves-day
Ok clearly this is just so it's the same as that for women so the feminists have one less thing to moan about but historically the safe limit has been something of an exercise in Bovine Guano anyway, the original 21 units a week was purely so the daily amount was not over the DD limit, nothing to do with health at all. So now we must endure this latest old pony on the alter of PC cobblers.
I don't believe that they wish to claim a safe level. But we know there are both pro and con to imbibing. The tighter they make a limit the more it'll get ignored. It's good to have info as long as we're not preached to and manipulated into feeling guilty or fearful. Life needs to be enjoyed so find your own sensible balance (hint: if you are off balance you may have had too much) and stick with moderation.