Why did Freddie become gay?

So a young man going in after a granny? EWW YES!

HIV was known to be something you had a much higher chance of getting by engaging in promiscuous gay lifestyle in the early 1980's. Freddie didn't get diagnosed with AIDS until April of 1987 regardless of what the movie showed, the movie was taking dramatic license. So the odds are extremely high that he contracted it several years prior to the diagnosis which would have been well after living that lifestyle was known to be a significant risk factor in getting the disease. So yes he knew or should have known as it was pretty common knowledge back then as I remember discussing it and the gay angle in college in the early 80's.

As for it being normal to act on one's desires, under that logic I hope you don't ever say anything about fat people because they are just acting on their desire to eat... and serial killers, well they are just acting on their desire to kill.. Get the point? A big part of being human and not just some animal is the having and using self control.

Yeah the knowledge about it was vague.

https://www.theatlantic.com/health/archive/2014/12/the-disease-of-the-century-reporting-on-the-origin-of-aids/383440/

On July 3, 1981, The New York Times published a story by physician and medical correspondent Dr. Lawrence Altman titled Rare Cancer Seen in 41 Homosexuals. The cancer was Kaposi’s sarcoma, a tumor caused by a viral infection and characterised by dark spots on the skin. While the disease usually struck older patients and progressed slowly, these 41 cases had appeared in and were quickly killing men as young as 26. Doctors were puzzled: The cause of the outbreak is unknown, and there is as yet no evidence of contagion, Altman wrote, noting that the patients had severe defects in their immune systems. There were few facts to be reported; journalists, like doctors and their patients, knew little about the disease. As one man recalled of his diagnosis for New York magazine in 1983: He said: You are immune-deficient. I said: What does that mean? He said: Nobody really knows.

From Time Magazine.

http://content.time.com/time/subscriber/article/0,33009,1050441-2,00.html

Aug. 12, 1985.

It is the virtual certainty of death from AIDS, once the syndrome has fully developed, that makes the disease so frightening, along with the uncertainty of nearly everything else about it. Despite the progress in medical research so far, huge questions remain about its origin and fundamental nature. In trying to understand AIDS, says Dr. William Haseltine, a leading investigator at Harvard's Dana-Farber Cancer Institute, we have moved from being explorers in a canoe to explorers with a small sail on the vast sea of what we do not know.

Then: http://content.time.com/time/subscriber/article/0,33009,1050441-4,00.html

Not everyone infected with the AIDS virus develops the deadly syndrome. Most develop a seemingly peaceful coexistence with the virus, says Dr. James Curran. They have no symptoms at all or very minimal symptoms, but they have persistent infection and are probably persistently infectious to others. Another group suffers a mild version of immune-system depression, with symptoms and signs that include malaise, weight loss, fevers and swollen lymph nodes.

What will happen to this group is the object of much speculation and study. That's the million-dollar question, says Dr. Michael Lange of St. Luke's-Roosevelt Hospital in New York City. The guess is that 5% to 10% of people who do not have symptoms but do have antibodies to the virus will develop AIDS within five years. There is no way to tell which ones will get it. It's like Russian roulette with one bullet and ten chambers, says Ronald Sanders of the Los Angeles health department.

As for where you were far more likely to get HIV in the 80's again in 1985 they still had no real idea:

http://content.time.com/time/subscriber/article/0,33009,1050441-5,00.html

The CDC has learned of at least 118 cases of transmission between heterosexual partners. Most heterosexual transmission seen to date has been from men to women, rather than from women to men, suggesting the possibility that women may be less efficient transmitters of the infection. However, at least 14 men have been infected by women, according to Mathilde Krim, a research biologist at the Memorial Sloan-Kettering Cancer Center in Manhattan, and health authorities are concerned about the possible role of prostitutes in spreading the epidemic. Curran thinks it may prove significant that about 15% of the men whose cases remain unexplained have a history of sexual contact with prostitutes.

AIDS appears to be almost entirely a heterosexual disease in the central African countries of Zaïre, Rwanda and Burundi, where it affects women and men in equal numbers. According to a Canadian researcher working in East Africa, Prostitution seems to have played a key role in African AIDS. Virologist Myron Essex of the Harvard school of public health thinks that as many as one out of every 20 people is infected, though not necessarily ill in Africa's AIDS belt, which also includes parts of Kenya, Uganda & Tanzania. Some researchers see this as a foretaste of what will occur in the U.S., but many disagree. They point to Third World conditions that may promote the disease. Among them the presence of feces in drinking water, the use and reuse of unsterilized needles in many small clinics.

Squalid conditions, poverty and a semitropical environment may also play a role in the high rate of AIDS in Haiti and, oddly enough, in parts of southeastern Florida. Belle Glade, Fla., with 46 cases, has the highest incidence in the U.S. "There is raw sewage on the ground and rats running all around, says Dr. Mark Whiteside of Miami's Tropical Medicine Clinic. Filth, insects and a high rate of tuberculosis, he suggests, might contribute to the epidemic.