Yes, you just let it go. Later on, cold damaged plants will "tell" you what's alive and what's dead.

The catch-22 for your tree is that, in general, recent plantings are more likely to be damaged by cold than are well-established ones. The most telling time will be during the 1st heat wave. Some plants may simply collapse.

Still, it requires a wait-and-see stance.

I have several specimens that look similar to your tree, and others that look worse. So. I'm also sitting on pins & needles.

The ironwood will be only marginally hardy in your area (minimum temp 15-20F) so not overly surprised to see damage. Actually, a bit surprised it survived at all, especially since newly planted.

Like many forms of eucalyptus, this may be more of a die-back-to-the-roots shrub in colder winters in your climate rather than a real "tree" :-)

I think catalina ironwood is a little hardier than it is often given credit for. Being large, established, and not getting too much water certainly helps - under such conditions I think suriving down to 10F or even lower might not be out of the question.

In any case I would agree that let it go and see what happens is the best advice - either it's in good enough shape to survive, or not - and if it does survive I doubt its form will be much affected in the long term, once the dead tips are replaced and drop off.

an established (8 feet tall, 6 feet wide) catalina ironwood in my neighborhood showed no damage from this winter (down to about 12).

i had a one in a wine barrel die in winter 08/09 snows.

so i'll also guess that the trick is to get them established.

I know of a couple that grew to some size in this area myself. Do not know current status of either. One was on Vashon Island, another in extreme southwest Seattle. The Vashon site was up on top of the island, not particularly mild. The other location was one that had comparatively high minimums during the time that the previous owner was present.