My source (listed in my post) said in one of his posts that it is "not impossible" (e.g. it MIGHT be possible if you had an open sore in your mouth or a gum wound), but in his experience in handling hundreds or thousands of cases (in a very active STD clinic), he has never encountered any case where unprotected oral was the route of transmission (but he goes on to follow up that he still won't go on the record to say "it's zero risk", he said it's something along the lines of 0.0001% iirc).

You can simply google his name and you'll see how well known he is in the field (as well as his NUMEROUS posts).

Anyway, in my experience, I personally KNOW plenty of females (escorts) who do CIM (cum in mouth) with HUNDREDS if not THOUSANDS of patrons (Cubao Sauna's legendary 81 [now 68 iirc]) does it with EVERY patron (and she said she services 3+ guys everyday), and Petite Keane (from AWR) also does CIM every time with me (and she's also always fully booked, she tells me she has at least 3 clients every day).

They've been doing it for years, 81 even swallows. And they have recent tests that show "non-reactive".