The decision to take the interview says a lot of things. Chiefs general manager Scott Pioli remains in place, but his job is tenuous at best. Chiefs chairman Clark Hunt is the one hiring the new coach, and there's just no way Pioli would fit in the organization if a coach like Reid is hired. Pioli's contract reportedly says he gets final say on his roster, which doesn't fit with a guy like Reid.
The Chiefs job is not as attractive as the Cardinals job, but this interview puts Reid in a stronger negotiating position with the Cardinals. It also gives him another option should he not get the Cardinals job. Reports have gone back and forth as to whether or not Reid is the heavy favorite to land the job in Arizona, but the Cardinals have publicly made it clear they haven't made any decisions yet.