Google has been repeatedly asking people to focus on user engagement. Browsers and toolbars are ways by which they can measure UE data. This includes clicking the Back button of the browser, which microsoft have admitted to use.
What Matt might have meant by saying they aren't using any chrome (or any other browser) data is they don't directly use the browser search history or any other data stored as part of Chrome's database Sqlite.
But they might still collect all UE data through cookies and other means (irrespective of browsers) and send back the essential UE data elements they measure, to their remote db used by the organic search algorithms.