whether the ibis protector is referred to as a cable protector or not i reckon the real reason for it is to reassure potential owners that their gnarly carbon bike will survive rock strikes-maybe calling it a downtube protector would sound like admitting they need it. SC have gone to great lengths to hype how tough that area of the carbon nomad is. Fragility to impacts is one of the main concerns that puts people off carbon (whether justified or not).
I was riding with pedalhead when it happened and I still cant fathom how unlucky he was and how freaky the impact muct have been, in the rock-free chilterns to find something that can do that to titanium (which is hard and flexible, 2 properties that should ward off such damage).