Briefly, yes, but didn't see this setting. When running in AP mode, many settings are greyed out. Didn't see it under basic or advance wireless settings.
I thought I remembered that AppleTV was connecting on 5Ghz. I did a quick test by pulling the ethernet cable and confirmed it was. It's moot as I'm hardwired to the satellite. This means that I should be running at the rate of the backhaul channel, but it seems that this is not good enough for this application.