I am disgusted by this, as well.
it is fairly simple, and simple to determine. I have yet to see a silver bay that I cannot tell from chestnut if I can at least see decent photos and barring that it is not a pinto in which leg color is completely obscured. Even then, if you look at accurate representations of parent's colors, you can get a good idea.
To choose chestnut when silver bay is the truth, is really misleading, colorwise.
Granted, color is sort of an inconsequential thing, other than LWO, obviously, but it helps for true identification of the horses and is a vital part of identification.
I love the AMHA, and if I had to choose just ONE registry, AMHA would be it. This ridiculous backwards move they have made, though, is a corker.
I will make my voice known that I am displeased.
Liz M.