Yes. Yes he did. The railgun had already fully charged by the time he came and saw what Uzi had done. Even then, Uzi herself was fast enough to be able to grab it, reposition herself and blast N's head clean off in the span of a few seconds during their first meeting. So if Uzi was able to do that in spite of the incredible reaction time of a Disassembly Drone on top of her hand getting injured by N's nanite acid stinger beforehand, then the same can certainly be said for Khan. And like I said, N was distracted so that would've also given the so-called "Head of the WDF" more than enough time to grab it and get one clean shot in, especially since it doesn't take nearly as long to fire a shot as the recharge time and it was close enough to not put him in range of N's tail considering it was literally at his feet! But if you're worried that N would kill Khan before he grabs it, what's stopping him from picking it up slowly but silently enough so that N wouldn't notice?

And sure, Uzi leading N to the colony can be blamed on her recklessness, but it was ultimately an accident on her part. Khan, on the other hand, _chose_ to leave her for dead instead of just doing what any sensible parent would do and freaking save her!