And last but not least, this adds to the urgency to draft a linebacker early in the draft. Had they signed Harrison, it wold have been much easier for the Bengals to pass on a player like Arthur Brown or Alec Ogletree in the first-round. At pick #21, the best value on the board may very well be at linebacker, and now the Bengals can not only address a need, but also draft the best player available.
And one other thing: Harrison was supposedly asking for a deal ranging in the $5 million range, and the Bengals have made it clear they want to save as much salary cap as possible in order to be able to (potentially) re-sign Andre Smith, while carrying over a large amount of salary over to next year to re-sign Geno Atkins to a deal that will make him one of the highest-paid defenders in the league. Those two players are far more important to the success of the Bengals than a 35-year old Harrison.