Being gay, engaging in homosexual sex, however you want to define it.
What Dr. Cameron appears to be saying is that homosexuals, male or female, die around age 60.
The title of his article in the referred scientific journal Psychological Reports is: Gay obituaries closely track officially reported deaths from AIDS. What that tells me is homosexuals die about the same age as anybody with AIDS.
The second sentence in the article says: This study provides additional evidence that the practice of homosexuality, with its attendant lifestyle, shortens the life of practitioners by about 20 years.. That doesn't say anything about AIDS.