As I said in another comment, that even assumes they were capable of knowing the driver was working for them. In their blog post they asked police to release details of the driver, with a statement saying that any driver involved in a serious law enforcement issue would be deactivated (i.e. fired). Then in the update, they confirmed that the driver (whose details were presumably released at that point) did work for them and was in fact deactivated as a result.

To my reading, it sounds like they simply had no way of knowing that the driver worked for them without the police giving them details on the driver.