If you'd said you did NOT have the gun loaded at all, I would have been on your side. Ammo in the mag tilts the decision, barely, in the GW's view. It's a good lesson for those of us that may travel on public or private land to get to our permit property.
I can understand the GW's view. If you'd seen a shooter buck, you could have cambered a round and fired.
I feel your pain. It hurts worse if you KNOW you're innocent and would not have fired your weapon illegally.
Others take note and don't even have a round in your magazine!