That's correct. They don't open in PM with raw rendering turned on. They don't enlarge (or do anything) when I double-click on them in the thumbnail view.
If I open the full-screen view by double clicking on a jpeg or another camera's raw file first, and then advance to an M9 raw file, the M9 raw file appears jagged until I click the Zoom check box to "1" (i.e. 100%") and then it shows a very small preview, presumably the one created by the camera.
Keep in mind that I'm using PM 4.5.4 from 2008, and the camera was introduced in late 2009, so perhaps that makes the difference. I plan to update to the current PM at some point, but I don't know whether that will make a difference for this particular camera.