Keith: "The fact is that gay men are doing better at limiting the transmission of the disease in their communities than are straight people at the moment."

Please explain/justify.
The rate of transmission in proportion to group size shows the opposite is true

OK, the words "rate of transmission" make the statement wrong.

The correct assertion would be "The fact is that gay men are doing better at limiting the the growth of HIV prevalence in their communities than are straight people, at the moment

Please look again at point 5, this is the important issue that kicked all this off.