Gay male here, and while I can't speak for everyone, I think I speak for the majority of gay males when I say: please don't do this.
Our biggest concern with these policies is not that we get left out, but that others who might need our help are unable to get it. Your boycott only serves to worsen the situation, sadly.
For vocal support, thankyou, please do continue expressing your opinion (though bare in mind that this kind of discrimination is at least based in logic, allbeit sometimes incorrect logic, and in protecting people, not discrimination for the sake of itself).
It's unfortunately not the organizations' fault. In general, they'd be thrilled to take anyone's blood after they screen it. The rule is specifically legislated.
I know they are trying to save lives but eliminating potential matches and discrimination is not the way to do that.