Without knowing the hardware/software under the hood I think it's impossible to know exactly which version it applies to. It could have been so bad that they didn't even need to dumb it down.
Nevertheless the logic of dumbing it down or purposely making the lane-steering component dumb makes sense to me.
Where AP1 was just good enough to be somewhat dangerous. At least to those that hadn't experienced things like trust lust or suddenly slowing down for no reason at all.
I'm really excited for supercruise even though its not L3. I am because it simply CAN'T HAVE truck lust. I'm also curious about what accidents will happen. With AP1 I noticed a pretty significant drop in my own situational awareness while driving. That resulted in a poorer scorecard of avoiding debris/potholes/etc.
If I was reviewing SuperCruise I wouldn't only review it, but I would review the drivers ability to handle unexpected situations while it was on. I imagine there will be a tradeoff where supercruise is safer despite the loss of situational awareness of the driver.