"a male hero would never be placed in the same physical condition"
Well, no shit? Men aren't "sexy" when in poses such as that. So far as I am aware, men are supposed to be very stoic/muscled/etc, not flexible and athletic.
If it were a male character in that position, everyone would be laughing their asses off and/or not consider it sexual at all.
Fact of the matter is, spiderman is an athletic and "flexible" superhero, he ends up in more "female suggestive" poses due to this.