Money's intemperate letter asserts that alcoholism is a matter of choice rather than a disease. The heart of his conclusion is his own definition of disease as "something you catch, either by accident or unknowingly as a byproduct of a normal, innocent activity." Though alcoholism does fit his description, it is more useful to look to an authoritative source of definitions.
Webster's unabridged dictionary says disease is:
2--Any departure from health; illness in general.
3--A particular destructive process in the body, with a specific cause and characteristic symptoms; specific illness; ailment; malady.
4--An evil or destructive tendency or state of affairs; as, bigotry is a disease of society.
In his effort to redefine words to fit his own moral pronouncement, Money displays symptoms of that social disease.