I must say that this seems a bit scary and possibly misleading.
If alcohol and Metformin can combine to lower BG then washing your Metformin down with a single malt appears to be an effective combined treatment.
Also, I very much doubt that the average T2 on Metformin alone carries around an emergency hypo kit just in case they have an alcoholic drink.
It also depends on what you drink. Beer has carbohydrate and so may well raise your BG. Alcopops and spirits with mixers can also be sugary, I think.
There is some degree of risk, but the link above does no quantify it.
There is no information on what percentage of people on Metformin suffer a hypo due to drinking alcohol, nor the percentage who suffer Lactic Acidosis.
I drink alcohol and I take Metformin.
So far I haven't had an identifiable hypo.
I may undertake some testing once my Freestyle Libre kicks in because it should be very clear how a shot of booze affects my BG levels.
I look forward to many a happy (strictly scientific) hour of dedicated research.
If in doubt, test with your meter to confirm the impact.