i'm not too upset about the term. personally i have Floyd as the best boxer of his generation. he may not have been tested fully at WW, but he was certainly tested at other weight classes, this is why i think people call him "the king", its not so much based on body of work at WW, but rather is reflective of his career accomplishments.
he'll probably go down as top 30 fighter of all time imo, and one of the three best defensive fighters.