See the problem with this is, even when seemingly unresistant, Steve will always be a threat to any normal soldier. In the comics, Crossbones is one of few who can go toe to toe with Cap (who can in turn go toe to toe with Gods), but Rumlow hasn’t reached that point yet. He’s just a good soldier — HYDRA’s best yeah, but he’s still only human so to speak — following orders.

And Rumlow’s a goddamn professional. Look at his fingers. Not on the trigger. He even admonishes Rollins several times to get the gun away from Steve’s head in acknowledgement that at that point Cap is clearly subdued and no longer a threat. Before then, however, until he was secured, he was. Especially when his main weapon is less than four inches from his foot. (And we all know that Steve doesn’t need the shield to do some massive damage.)

Because Rumlow knows, has seen first hand, what someone of Cap’s strength and potential can do even when seemingly docile and unresistant. And don’t forget, they had him surrounded in a goddamn elevator with gun wielding guards on the other side of the doors and he STILL took them all out and got away,

Another thing, that kick. It’s aimed to push, not to injure. It’s too far forward to cause damage, and it’s aimed at the back of the knee, not the side (which it could hurt. Let me tell you, ow, fuck), especially at that angle. It’s meant to push him off balance so they can more easily subdue him.

Rumlow is a dick, but he’s also a badass who knows what he’s doing. He doesn’t need your help in making a name for himself in either category.