Agree with you entirely. There has been a huge amount of academic research into the impact of alcohol consumption into health though, and this is then summarised when academics attend meetings with government officials. That evidence is then
http://www.medicalnewstoday.com/articles/236476.php
If you take a look at Google Scholar https://scholar.google.co.uk/ there are many studies into the impact of alcohol on liver and coronary issues.
Sally Davies, who is associated with the comments you refer to, is a doctor rather than a politician. I think having a chief medical officer who is independent of the pettiness of party politics is a positive rather than a negative.
This is already out there and leaving two days for the liver to recover seems reasonable but not particularly scientific, for me it still seems quite extreme drinking 5 days out of 7, but hey ho presumably not.
I am guessing drinking a glass or two of wine each day is unlikely to impact too dangerously on someone's health ahead of someone like me that rarely drinks during the week but might have the odd blow out (middle aged laughter rather than teenaged West Street kind of blow out) at the weekend, irrespective of any current science I will bet (in a gamble responsibly kinda way) that me or my example will not have any serious health issues due to our alcohol habits but each would be outside of the these current guidelines.
It seems logical that if my Italian one glass of good wine per day man or me the midweek teetotaller falls outside of these boundaries the government would want to modify my current lifestyle choice of how me and my mate treat alcohol, thats the point really I do not wish them to.