Really, any respectable company in this situation would simply flag the account for a billing problem, deny the card, and let the customer try again. At which point, any legitimate customer will go, "Oh, guess they don't take Apple Card" and use something else. It's the same effect (account can't be used, "fraud" with the Apple Card if it exists is dodged) but is not nearly so user hostile as this... mess.
Google's opacity here seems like it could only really have one benefit to the company: They can shut down any account they don't like, and since they're always vague with the reasoning, they don't necessarily have to have a valid reason. Their whole "you know what you did" approach is just uncertain enough to cause the victim to doubt themselves and be unlikely to mount a defense. I don't know what their actual motivations are (I know it's popular to hate on Google, but I have a hard time believing they're pulling stunts like this on purpose) but it looks bad no matter how you slice it.