This data is probably very skewed.
In the 1950s and 1960s, there were just a lot fewer gays. Even if they had some interest in the same sex, many chose to get married to the opposite sex and follow a traditional lifestyle. Hence, in 2005, practicing gays are a smaller portion of the Baby Boom generation than Generation X.
Hence, if you sample obituaries, there are going to be many self-identified "gays" in the younger generation, and fewer in the older generation. So the ratio of Baby Boom: Generation X deaths will be skewed.
You may be right, but there are a number of studies that support Dr. Cameron's study. He ran a similar study 15 years ago with the same results with other organizations supportied him, and now the CDC is reporting the same.