As someone who has used fly rods and spin rods I hate to see this. I'm an old man but I have a short fuse and would have given them as much shit as they gave you. I only fish with a spin rod now and fish mostly the Arkansas for river fishing but also lakes and ponds or course. The same attitude is on the Ark from fly fisherman. They think they own it.
As far as I know, there's no place in Colorado that's fly fishing only. Fish anywhere you want and tell those to stuff it if they don't like it.
Life is hard, but it's a lot harder when you're stupid.......John Wayne