So Vanc to SD is fine, (not US to US) Hawaii to Vanc (not US to US) is fine but Hawaii to SD is not fine because they are both US ports. That's likely why Disney is based out of Vancouver for the Alaska cruises.
DCL sailed round-trip to Alaska from Seattle in 2012, with a foreign port stop in Victoria, BC. I think they moved back to Vancouver because they got a lot of complaints about their crappy Seattle itinerary!

Even when the Olympics were in Vancouver, it only took us 30 minutes to cross the border. And that is the longest I've ever waited.