The whole beer thing winds up being a definate "it depends" If he's using it as a coping mechanism and it's 3-4 a sitting, that's not good. However, the nutrition hand out the oncology department of my hospital gave me mentions that a Guiness a day is good for building up nutrients and helping to keep weight on. Also mentions that it helps to stimulate the salivary glands and suggests it with a meal.

My wife limits me to one pint a week, I can have with once a week beef curry (she's strict!) I find the pilsners/lagers such as Budweiser tend to sting somewhat and if I were to do any social drinking irritate the already scorched areas of my tongue.
Bob