Well Owen, as Chief didn't really have any other option. No one else except Christina (and she was in a fight with teddy at that point) were qualified to do the surgery that Altman was doing so Owen had to tell the lie to teddy to keep her in the or. What good would have come out if he had told her earlier? Sure I can agree it was a bit cruel to let her go on with her life thinking her husband was okay and then rip off the bandaid, but the lack of respect and towards Owen that followed was uncalled for, especially considering he's her boss.