no it's not, there are certain circumstances that have to be met.
The main ways people have gotten are being the receptive partner, either sex, and needles.
Lots of people got it mysteriously, there was a newscaster who got it, black fella who died, one of the early guys. Isaac Asimov got it from a blood transfusion and they lied about the cause of death to spare his family the embarrassment. A lot of guys like Rock Hudson or Liberace were once and for all pulled out of the closet, either before or after death. You see, they tried to bury Liberace and say he died from something else, a nasty coroner had that plan interrupted and released the full autopsy results.
that one lady, Amanda Blake, an older actress got it somehow.
Not everything adds up for me but I would be a long ways away from being like Tommy and saying it was a myth. I did some reading on it because my sister died of it.