His speed has to be tempting to throw on a practice squad and try to develop the rest of his game. It costs the Niners next to nothing to do it, so why not? Maybe they think he can replace Ginn down the road.
I don't know that I'd say they're "loaded" at WR. I think Crabtree is about as good as you can do for a #2 wideout, but he's not a go-to guy. Manningham is another complimentary player. Moss is on his last legs. I know it's early, and he plays a position that traditionally takes time to develop, but the Niners have to want a do-over on that AJ Jenkins pick. I wouldn't argue with saying that they're deep at WR, but if somebody asked me which NFL teams are loaded at WR, I doubt the Niners would even be among the first dozen teams I'd mention.