I usually hate silly, excessively litigious suits about nothing, but I actually agree with this one, at least partly.
Imagine that guy was your friend, and had you take the bike out for a spin. It is not unreasonable to see the ABS cutout, and assume that there is an ABS system installed, and that the light isn't on because the system is functioning. Some clown pulls out in front of you, and being a well trained ADV rider, you react as trained: If it has abs brakes, pull hard, press hard, and hold on. Unfortunately, you lose traction, and crash. If you had known that it lacked ABS brakes, you would have done proper threshold braking, as you were also trained to do.
I think it is irresponsible to leave ambiguity in this regard. Maybe not $10 million irresponsible, but irresponsible nonetheless. My BMW K75 does not have ABS, although it was an option when new. There is no light, a place for one, or any other indication that would even suggest that it has anything besides the wooden and lockable, but excellent brakes that it has.