Pedestrians aren't banned, just people asking for things. In my experience, if a cop says one thing in court, and a bum says another, the judge (who will generally know the cop) is not going to believe the bum. Meanwhile, you're sitting in jail waiting to see a judge for a week, or two, to plead not guilty because you pissed off the cop in some way, and they don't trust you to not run off because you don't have a residence and you probably aren't going to show up for trial unless they make you.
Granted, it's the worst case scenario and you're almost certainly going to just get a warning, or just cited and released, but Nevada cops can be some pretty big pricks. If you're coming from California way, just grab a Megabus, it's $20 and hitching Nevada sucks anyway. I stood on ramps there for 4 days trying to hitch out of Vegas. It was hot, there was no shade, and I got several warnings before I'd been given enough money (just from hitching) to get a Megabus out of that craphole. Accidentally came in on a train out of SLC into Nevada summer.