[DannyBee]

and now, they never will, which would be the focal point of any antitrust attack.

Also, the DOJ does not have sole authority to challenge. Here is the breakdown for telecommunications (taken from DOJ website, http://www.justice.gov/atr/icpac/3b.htm)

  Telecommunications. Mergers involving telecommunications    
  service providers usually are subject to competition policy 
  review or challenge by:


  One of the federal antitrust agencies (only the DOJ has 
  jurisdiction to review mergers involving telephone 
  companies; both the DOJ and the FTC have reviewed mergers 
  between cable television firms);

  The Federal Communications Commission (FCC);(8)

  The PSC of each state in which the parties do business 
  (although most state PSCs lack jurisdiction over cable   
  television mergers and some lack jurisdiction over mergers);

  In the case of cable television, county and municipal   
  authorities with responsibility for granting and overseeing 
  cable franchise agreements;

  The attorney general of each state in which the merging 
  parties do business; and

  Private entities such as competitors to the merging parties.
  As with mergers involving electric power firms, review by 
  any of these entities is nonexclusive. Approval of a 
  transaction by one entity does not preclude a separate 
  challenge by any of the other entities, nor does it bar 
  another entity from seeking adjustments that exceed 
  concessions that resolved the concerns of other bodies.

I suspect the DOJ (who has sole jurisdiction in telecommunications) will object, and that comcast is just willing to fight it out in court.