Fine. Just call them the perverts that they are.

As for using the CDC's "MSM" designation, that doesn't make sense to me. In some ways, it is more inclusive that some gay people cannot admit they are gay. "I'm straight! But I like men!" Plus there are bisexuals who want to be seen as bisexual. Then of course comes rape and incarceration. Not everyone who is "gay" in prison wants to be, and sometimes what they are doing is more akin to mastery play. It is more about dominance and humiliation than sexual pleasure and a way to keep other inmates "in their place."