From the camera angle close in on Steve and the cut to Tony shielding his face, yes, the movie took the POV of Tony, who thought that Steve was going to bring the shield down onto his head. In a wide shot, it would have been MUCH more obvious that Steve was aiming for the arc reactor. The Russos didn't choose that, they chose to take Tony's POV in that moment. Movies take a POV scene by scene, and they do it using camera angles and editing. Just because there isn't an inner monologue or some soft lensing going on, doesn't mean it's a fantasy. Every story has a POV.