Yes, items with Dylan's scent had to be brought from Colorado Springs, because the dogs couldn't get a good scent of him from anything in the house. It seems his clothes from the day before were taken with him. Possibly the pillow and blanket from the couch had been used by others and the scent was mixed. Or he never made it to the house. Those are the only logical reasons I can speculate about.
I just wanted to say the the word "abduction" legally only means taking someone from where they are willingly to someplace else against their will. It's a subtle distinction sometimes. For the sake of illustration, if Dylan was hitchhiking (which I don't really believe, but just to show the point) and someone stopped and he got into a vehicle willingly, he wouldn't be considered abducted yet. It would only be an abduction at the point that he said, "Let me out here" and the driver didn't do it. However, if Dylan was walking down the street and someone pulled over and forced him into a vehicle, that would be an abduction immediately.
It's the point at which the abductor begins to act against the person's free will to be where they choose to be, in other words. Abduction can be perpetrated by a stranger or an associate or a relative.
So, when LE says they expect an abduction, it doesn't mean that they're saying someone grabbed him and forced him physically. That's just one scenario. Technically, a live person or a dead one can be abducted. Removing a body from the scene of death is a form of abduction.
So, LE saying that they think this may be an abduction doesn't really tell us a whole lot other than they think Dylan was interred with in some undisclosed way.