Sorry but I’m gonna have to call that claim false.
I am 100% homo, perfect Kinsey 6 and I happen to fit this statement perfectly. But I also know that “perfect sixes” aren’t the only gay guys on that scale.
It is incorrect to think that no guy (on here or not) who identifies as gay wouldn’t have sex with a woman. There are LOTS of guys who view themselves as gay who will happily, under the right circumstances, be quite fine having sex with a woman. And if the scene was with other guys involved as well, as the OP sets it up, that probably gathers quite the crowd.
So, to the OP, yes there are going to be guys out there quite happy to jump into your scenario, gay identified, bi identified and even straight identified. These last will still dabble now and again with male-male sex, just as there are gays who will dabble in male-female sex but still view their main and strongest interest as being other men.
If this were NOT the case, there would only be two levels on the Kinsey scale. But there’s not it goes from 0 pure straight to 6, pure gay. A shit ton of people sit in the 1 to 5 area.
Making absolute statements surrounding human behaviour will normally prove to be off the mark, there’s way too much “grey area in the middle” on nearly any issue.