This is a much better situation to sign autographs in than any other I've ever seen. Usually the celebrity gets so overcrowded with people desperate to shove their piece of memorable in that it can seem claustrophobic. With a fence in between them it's really not so bad. Maybe celebrities should walk around with a small fence around them so people can't overcrowd them. You just have to hope that crazy fans don't start climbing the fence to get inside with you. A signing session turns into a cage match.
Nowadays Star Wars is so big that they have to hide where they're filming so that people don't come swarming the set. Things were a little more manageable in these early days, but you can still see how popular Mark Hamill was even before all three original movies had come out.