They would have to stock more parts, can't get old parts just like us, want to sell new bikes, training young guys to work on an occasional old bike is expensive, want to sell new bikes, takes too much time & often more than a bike is worth, want to sell new bikes, might not be able to get the bike out of the shop quickly, want to sell new bikes,outcomes might not be what the owner expected, want to sell new bikes, takes away from more profitable jobs, want to sell new bikes, might get stuck with a virtually worthless bike when the owner won't pay up, would rather sell new bikes, etc, etc, etc, would rather sell new bikes.
The least these buzzards could do is train a mechanic then fire him so he could open his own side business and take care of the Honda dealers' bikes!!