The pose is not so much to show that it was a flyrod caught fish as it is a convenient way to hold the rod when your hands are full with the fish. Not many people want to leave a $1000 of rod, reel and line loose in the bottom of the boat (or in the surf) while trying to quickly get a pic and get the fish back in the water.
A pose that makes a good shot might be for the photographer to lay the rod in the crook of his arms, take the pic, then grab the rod again for the angler.
I agree that the rod in teeth looks goofy. I also think it's a nice fish.
