Apparently only 'high-risk' men who have sex with men should use Truvada as pre-exposure prophylaxis. Who are these high-risk men but those who tend not to take precautions? PrEP, if it works, is a precaution. Therefore, the only people likely to take PrEP as recommended would be considered to be low-risk.
But is Truvada really intended for those men who have sex with men who are at highest risk of HIV infection? I don't really believe that. I would suggest that Gilead, the manufacturers of Truvada, intend to break into the recreational drug market. I'd say they want people who don't wish to use condoms to use PrEP instead. I think that's what the whole pharmaceutical industry wants.
The US Center for Disease Control (CDC) has not approved the drug for preventive use. Yet they issue guidelines for its use as PrEP. Anyone can use Truvada if they can get hold of it and any doctor can prescribe it. I think we can be fairly certain that it will be prescribed and used as PrEP, as a recreational drug.
After all, people who are at high-risk of becoming infected, well, take risks. CDC not approving it as PrEP, but issuing guidelines, is not going to make people think twice. And whether Truvada results in "78% fewer cases of HIV infection" or reduces "infection by 44%" will make little difference to those who may already be engaging in have unprotected anal sex.
CDC and others are giving mixed messages and they seem to be doing so knowingly. If people listened to advice, they wouldn't be at high risk of being infected with HIV. Therefore, I suspect this whole scenario is calculated to maximize profits and minimize risk for the pharmaceutical industry and has little to do with the risk of contracting or transmitting HIV.