10 litres(of normal strength wine) would be a lethal dose for the average man in the street, but to a hardened dipso might not even touch the sides.
Also no mention is made of what it was he had drunk. Wine, in the UK, legally can be upto 12% ABV. Weaker wines are common, and much cheaper (Lambrini is actually somewhere near 3%ABV, again IIRC). So basically the level of alcohol imbibed could be anywhere between the equivilent of 10 litres(20 pints) of lager and 40 litres (80 pints) dependent on what was drunk. For a harden alco this could be the difference between a bad head the next day and death. For your average Joe it would be the difference between death and full on never coming back death.
I don't know the full details of the incident, but chances are if he has a real problem then it would be towards the lower end of that scale, not the top.