Of the papers submitted to a conference, it might be that reviewers don't offer suggestions that would significantly improve the quality of the work. Indeed the quality of reviews has gone down significantly in recent years. But if Anthropic were going to submit this work to peer review, they would be forced to tighten it up significantly.

The linear probe paper is still written in a format where it could reasonably be submitted, and indeed it was submitted to an ICLR workshop.