There is another reason for glass bedding a muzzle loader. I have a Renegade stock, it has a 1" barrel channel, but I put a 15/16 Green Mt. barrel, that I came across, in the stock. Also, as far as accuracy is concerned, it is hard to beat a Douglas barrel. I have a custom 36 cal. rifle, that has a Douglas barrel. It out shoots, every other gun, that I have. Who knows, maybe those guys did what I did and put a 15/16 barrel in a 1' stock, and had to bed the stock to make it fit.
Then they might have thought the glass bedding would improve accuracy, when even, just the barrel alone, would have been good enough. Worked on the brains of the competition, and that might have given them the edge, that they needed.