I've never owned a car made by GM, but a decision like this guarantees I never will. I don't buy their take that the safety issues are because Android Auto and CarPlay are buggy and have connection issues and other crap that cause people to use their phone directly. I've only had a new enough car to use Android Auto for a year and half now, but I've literally never encountered a bug that required me to touch my phone…
Ack. From my experience, connection issues with Car Play are 100% due to the shitty software on the car's side and never on phone's side.
I regularly have connection problems (i.e. black screen in Car Play when entering the car - a Fiat with UConnect 5). They can _always_ be resolved by rebooting the cars's entertainment system. _Never_ by rebooting the phone.