I have to admit I find it a bit baffling. If Cunard and Princess can be well-run together in California why not send Seabourn there?
The one thought I have is that Carnivall Corp sees Holland America as an under-utilized asset and they feel they can get more bang for Seabourn up there than they are getting in Miami. Plus Miami doesn't have another lux operation so mkaybe they don't "get it" that those kinds of calls require a higher level of service than the call center for Carnival Cruise Lines.
Obviously, they wanted a change in something, and my guess it has to do with the back-end services for travel agents Eric outlines in the Blogpost he linked to.