I drank anywhere from 375ml ( close to a pint I think? ) to 750ml ( just shy of a true 1/5th) a day 3-5 days a week at the end.
I had shakes and trouble sleep , cold sweats and one night a near panic attack. I never hit DT's though.
It would be hard for me to believe a pint every OTHER day would be that strong , but like said above I guess everyone is different. Mine had only been going on for a year or so and at that high level only about 6 months.
If he's been doing that his entire life , his body is likely reacting alot more strongly.