Probably. "Confirmed" just means that, if someone saw one, nobody was able to officially corroborate the sighting.

I hadn't seen that news about someone seeing a grizzly in the Cascades. I've been to the North Cascades several times. Ranger guidance has always been "There aren't really any meaningful populations of grizzlies here. We're pretty sure that, if there is one here, it's a transient from Canada."

You still have to take bear precautions there because of black bears, though.