Update - I called back with flight info that would work for us to take HA from LIH to HNL and then take the nonstop on AK to PDX. She put me on hold for a long time to see if she could do it and then said she could. Adds an hour to our trip but a layover in HNL instead of SEA is better anyway. Ended up getting $700 each credit for future travel.
oh and I asked again why we were being asked to move. She gave me the line about a different plane. I know when I booked it a. 737-800 and she said that’s what it will be so I’m guessing some VIP (why not just charter a plane?) or maybe employees.