Not true. Sasuke caused a terminally ill man to overexert himself by using Susanoo which led to Itachi's death
I don't think you understand what I have said before. Itachi was not fighting at full strength and his number was already up. Essentially means he 'lost' before he even began to fight as zetsu alluded to. And in that sense, there was never a battle and so such victory really. No matter how sasuke takes it.
You must be registered for see images
Furthermore, itachi had no intention of killing sasuke. His life ambition was protecting him. It makes sense for him to die by 'sasuke's hand' as some kind of atonement. The timing couldn't have been better! So that's only a metaphorical defeat. He was dying and wanted sasuke to be there.