I agree it's totally perplexing. GM doesn't have a moat, all of their vehicles have competition.

Could this just be a bluff/negotiation tactic or something?

It seems so perplexing to remove these features, rather than giving the option for Android auto and car play along with their own android platform. If their own system has better native functionality, people will see this as a selling point. If not, they're free to ignore it.

Cars are not TVs. It's a major purchase that somebody will be using for years, so people will pay attention to this kind of detail. Surely they know this?