There is so much judgment and homophobia on this thread, even for mumsnet!
There is nothing wrong with consenting adults freely agreeing to have anal sex. People have sex for pleasure - that’s fine, and the way in which they consensually choose to do it is fine.
Practicing safe, healthy sex is really important but what the hell does that have to do with whether it’s ‘normal’ or not? There is no such thing as normal, people have sex in any number of kinky, unusual and bizarre ways and that’s absolutely fine as long as they’re being safe and practicing enthusiastic consent.
As for all of this bullshit about aids seeming like a gay disease and people having sex with apes, this is just a wild misunderstanding of the historical and medical context of this disease. You should be more careful about sharing harmful stereotypes (even if you’re saying you don’t believe them) as it’s clear that you have a shallow and incomplete understanding of the history of that illness.