I agree, people should make room for other. If a bus or train is full seat-wise, I always give mine to an older person, or person with many bags, or kids, etc. I'd often prefer to stand than sit, if sitting means being uncomfortably compressed.
The part I disagree with, is that men sit more spread out than woman as a show of male dominance of public spaces. This has been part of the view behind the idea of "man spreading". I too don't get the spread eagle sitting pose. I'm 6'2'' with thick thighs and don't sit that spread.. Tho if it made him comfortable and no one needed the seats, I feel he should be free, and women as well, should be free to sit that way. Also people should be free to say, that person is sitting unusually, because they are.