Let your agent find out about this for you. Personally, I've not heard about this - so it's a new one on me.
If you leave Honolulu and go to Ensenada, that counts as a foreign port, which is why they go to Ensenada and not directly to another U.S. port. Then when you leave Ensenada and go to Seattle, again, this qualifies as being in one foreign port. And then when you leave Seattle to do an Alaskan cruise, one of the ports is in Canada, which again satisfies the foreign port requirement.
There are some Hawaiian cruises that will do a roundtrip from LA - they leave LA, go to Hawaii, then make a 3 or 4 hour stop in Ensenada, and return back to LA. This satisfies all the requirements of stopping in a foreign port.
So again, don't know where you're getting your information, but I don't believe it should be a problem. I've not personally encountered this exact situation, but I would definitely have your agent find out the specific requirements about this and it'll be interesting to hear what they have to say.
If it wasn't the weekend, I'd call my brother-in-law at the State Department and see if I could get some information on this as it sounds interesting to say the least.