Not quite...
As there were planes to fly this route last week, I doubt the Boeing strike had much to do with it.
What I'm saying is that loyalties are forged in the tough times. I used to fly AS exclusively on the west coast. Frequent service, comfy F seats etc, etc.
Now no more F seats, no more Mexico flights, etc, etc.
It seems that PDX is a fair weather hub for AS. The first to go when times get tough, while they maintain some loss making flights at SEA for connecting purposes.
Now my dollars go to WN (no F seats, but more flights and grown up planes) for OAK, or AMTRAK for SEA.
When things get better, and eventually they will, AS will restore some PDX service. Perhaps by then, Virgin America or some such upstart will come to PDX and compete with an AS that has shown where its loyalties lie.