Just because the 1K desk says you can't standby for the earlier flights doesn't mean it's true. The flight coupon thing can be an issue but it certainly can be overcome by an airport agent if they are willing to create an extra coupon for you. I have done it before. The issue is that it's a small to medium amount of typing for them so it's possible some agents will say no. But if you really want to fly earlier I would go to the airport and request it and I bet you will be successful.

And as for the story of someone getting punched.. I think that's a line of BS the agent gave you as an excuse. Since the beginning of time many agents have refused to give out wait list position over the phone...either because it's not allowed by policy, or because some don't have access to it or just don't know how to look it up. It's doubtful there's been a sudden change.