You are not incorrect, but if you listen to the interview that Dale gave with Fred the day of the import draft, he indicated that the Red Wings 'know where we stand' with Seider, and 'everything is in their hands'. Perhaps it's just a breakdown in communication with what you've heard and typed here, but I don't think they have 'moved on', I believe they know the situation is out of their control and acting as such.
Dale also made mention that they would make room for Seider if they need to do so, so drafting 2 imports isn't an indicator of anything other then them simply covering their bases. Odds are Seider will not be in Owen Sound this year, so not drafting 2 imports would leave them without one for the year. We have no idea what Straub will become (he seems to be a complete wildcard for many), but drafting him is no indication of Seider's future.
All you have to do is look at London last year, they had significant indications that Boqvist would be assigned to London, but they still drafted two imports to cover their basis. This situation is no different, outside of the fact that the odds Seider coming are significantly lower it would seem.