Everyone knows everyone at my park. And in letting people ride it, a few of them actually ended up getting their own which is awesome. So if letting people ride my scooter for 5 minutes helps to grow the sport i see no harm in it. If you have a descent scooter its going to be hard for someone to mess it up if they don't usually ride seeing as they will likely be taking it easy. I don't see the big deal in letting people ride your scooter.
I must say I agree with that whole part. I really hate when kids with perfect set ups won't let any one try out their scooter.