No. "On an average interview at google" is not really the same thing. It's not getting at the same point.

Taking a step back: If preparation can give a bad candidate a good shot at passing the interview, then that interview process is broken.

If you have a company with a bad implementation of whiteboard coding interviews (for example, who just pull questions out of Cracking the Coding Interview), then it's absolutely true that a bad candidate could pass this process.

This doesn't mean that whiteboard interviews are broken. It means that this company's implementation of whiteboard interviews is broken. There is a difference.

For Google specifically, their implementation is decent, but not ideal. A bad candidate would have low odds of passing an average interview at Google, but those odds are not as low as I'd like.