I don't think it's really a slippery slope. It's easy to say "no motor-powered vehicles", including eBikes. A horse is far more destructive to trails than bikes are. Even "no bikes except where allowed" would probably be fair. You could ask decision makers to designate a few trails as ok.

It's very clear that Wilderness areas are not meant for commercial exploitation. I believe a few of them have grandfathered in grazing rights, perhaps to get them over the line politically, but that's about the extent of it and I would not expect that to change.