Keith - You posted this yourself -

PHE.
" Get tested regularly for HIV if you are one of those most-at-risk:
a. Men who have sex with men are advised to have an HIV and STI screen at least annually, and every three months if having unprotected sex with new or casual partners."

So not all agencies are making the mistake of equating the at risk groups with all homosexuals. And what makes you assume that "it is taken as understood etc." Nothing should be taken as understood. Particularly on the internet. Not everyone is capable of understanding.

DtG