One would think that Walter Williams of all people would at least mention that analogy to the fact that it is not considered acceptable to discriminate on the basis of race, even though black life expectancy is less than that of whites.
The common factor is that like race, whether a person is gay or not does not appear to be under conscious control, whereas smoking and obesity are to a great extent. If we were going to discriminate on the basis of innate factors, then perhaps higher insurance premiums should be charged on the basis of familial health risk factors or DNA analysis.
If one assumes that homosexual attraction is innate (which twin studies demonstrate pretty clearly it is not, at least at birth), that still does not mean that engaging in homosexual acts is not a specifically chosen behavior.