It makes sense for the guards to say "Step away" because honestly they have to watch their own asses and to do that they need personal space, there are several reasons for guards to tell you not to get too close. This can range from them suspecting you to have sticky fingers, you planting a bomb, they don't want you more than an arms length away for fear of wasteland rape, your breath smelling like boiled shit(No toothpaste in wasteland, what used to be a toothpaste is solidified, and makes you hallucinate because of how long it's been expired, probably killing you after your trip or during it), you could be carrying some horrid disease that could wipe out an entire NPC faction, or you're just really annoying.
Back in the day when I actually played, if someone stood too close to me, I'd blow their fucking skulls off regardless who they were... And I was generally a nice guy... If a nuclear holocaust were reality I'd be even more certain to blow your fucking skull off, because you're pretty much in my personal space, and I don't want you trying to rub up against...
On another note, running past these guards does not get you killed, this makes me think this suggestion is trying to lift anti steal/rape defenses, because the only way you can really get them to attack you is staying in their personal fucking space.
Inotherwords, give a G some space BITCH!