If the screen is free of debris then a rubber tip is simply not going to scratch the screen. Even the cheap styli that have rubber tips won't scratch the screen. What I wrote was to give you an example of how, using a rubber tipped stylus, the screen could get scratched.
Lots of people are claiming at the Adoint Jot Pro has scratched their screens. The guy you spoke to telling you can any rubber tipped stylus can scratch your screen if you don't use a screen protector is full of it (unless there is sand on the screen). I think they are worried about all those claims on Amazon.com against them. I'm afraid to try the Jot Pro, however, on the off chance they those tips might have some kind of material in them that is harder than the screen of the iPad. If they do, that might be the reason for the scratches, if those claims are true.
I have my old Droid Incredible smartphone sitting right here (it recently quit working). I just took a fingernail file to its screen, using the sharp pointed end. I could not produce a scratch in its surface. Then I took a pair of scissors to it. Pointy end only. Twice...using hard force. Nothing.
I also have some cheap styli here too. One has a rubber tip and the body is made of Aluminum. Obviously, the rubber tip isn't going to scratch it, but I took the AL end and rammed it on there. Still, no scratch.
It is really hard to scratch the screens, even when you try!
IMO, the best reason to use a screen protector is to control fingerprints, because they are gross to look at. But I don't think one needs them to prevent scratches, unless you play in sand a lot. Of course, I'm not going to experiment with my iPad to test this out. Lots of people like screen protectors, though. I used my iPad 2 for a year, sold it to Amazon, no screen protector and no scratches. I do keep a skin on it and keep it inside a case. The AL body will scratch much more easily than will its screen.
