At the Appleseed I attended in Illinois, we had only 25-meter shooting, and the people with Ruger 10/22's with slings and the Tech Sights had the easiest time of things. But I shot it with a 1970's era AR15 SP1, and my son started the day with a Marlin Model 75. My other son lost a magazine and did the whole thing with only one. There were bolt actions on the line, too.
You do want something with removable magazines, IMO, if you can manage it. But they don't care if you're using a scope. Honestly, I realize they say a bit about iron sights, but they don't seem to teach anything that's actually relevant to which kind of sight you use. Shoot what you have. A reliable rifle with a couple of magazines is more important.