Steve never assumes Diana she can’t do things ‘because she’s a woman.’ He assumes, rather, that Diana has the same vulnerabilities as her fellow Amazons, a number of whom he personally watched get felled by bullets whilst battling gun-weilding fascists on a beach.
This is an entirely fair assumption to make considering even Diana, at the beginning of the film, does not realize that she is a god among mortals. Her mother raised her to think of herself as human.
Steve starts off assuming Diana is a highly competent, albeit human warrior, because she introduces herself to him as an Amazon, and he’s seen the Amazons in action. He knows what the Amazons are capable of. He’s seen them die from bullet wounds. He’s also seen them win a battle against technologically advanced fascists using only bows and arrows and parkour.
As soon as Steve realizes that Diana has godlike powers, he adjusts his expectations accordingly. He no longer expects her to have the vulnerabilities of a human warrior once she’s proven otherwise.
The thing about Steve is, he’s not consciously trying to be a feminist ally. He’s just reasonable.
He makes logical conclusions based on his observations. He draws new conclusions when he observes new phenomena that contradict his previous assumptions.
He uses basic common sense.
And that’s the beautiful thing about this screenplay. It does a great job of illustrating how illogical sexism is, and how diametrically opposed sexism is to common sense.
If you discover someone you were flirting with yesterday can repel bullets, the logical reaction is awe. A reasonable human being would be awestruck. It would be absurd to get defensive. Yet we, the audience, expect the male protagonist to get defensive because that’s what we’re used to seeing from male protagonists.
We are so used to male protagonists with comically inflated egos, that it’s shocking to see a male protagonist put common sense ahead of his ego. We are so used to seeing male protagonists make sexist assumptions that we are surprised when they instead draw logical conclusions.
The opposite of a sexist is a reasonable human being.
