"The second comment is about "really smart math guys"
I know that it was not intended to say anything not polite, (please, please, don't be offended) but it seems express the idea that maths is a Male stuff."

First, Im not offended. And I'm aware that the connotation of "guys" is "generally" masculine. However, I was using it, as I often have, in a neutral sense. I have been guilty of saying to a class of students of both genders, things such as, "You guys better not be late." No one thought I was excluding the ladies from this warning. It may be generational or regional, but I've also heard the term "fellas" used in the same way.
Mrs. Rice, my 10th grade algebra teacher, would speak on my behalf, if she were here.