[Inziladun]

Perhaps, since Théoden was not a personal witness to the death of Théodred at the Fords of Isen, and he had so lately witnessed the atrocities of Saruman's troops in the Westfold and at Helm's Deep, it was the latter events that stood the clearest in his mind at the time of his encounter with Saruman.
Théodred's death could well have been one of the factors leading to his rejection of Saruman, though.