Well, I have a little experience with Fords....
Comp Cams doesn't make/sell a steel distributor gear so they are probably a little reluctant to push something they don't sell.
The short and skinny of it is that a bronze gear or polymer gear just don't last long for street duty. A steel gear will last indefinitely if it's installed correctly and I use nothing but steel gears in all of my engines with billet steel cam cores.
You can put a bronze gear on it, but just keep a constant eye on it, because it will wear.