There's stretching the truth and then there's irl retconning of when Mercury found out about his HIV diagnosis and using that as the motivation for the Live Aid concert which is what this movie does.
That wasnt his motivation in the movie. He finally realized that the Paul guy was a snake who had been sabotaging him for a long time and that hed been unhappy with his life for years, so he decided to reconnect with the rest of Queen and do Live Aid with them. He told them that he had AIDS but he also said that he didnt want them to make a big deal about it or tell anyone. ---
