מוסר אויף במדבר 3:23

In the words of our sages there: "Surely Moses did not plead with G–d to let him enter the Holy Land merely to taste its fruit!" While on this subject let me explain Rashi's comment on 3,24. He divides his comment into פשט and דרוש. As far as the דרוש is concerned I find it difficult to follow him because, if he is correct, the Torah should have written אתה החילות והראית, "You have begun and shown me." I therefore prefer to deal with the פשט part of his commentary: that Moses felt that because he had been allowed to defeat the kings Sichon and Og on the East bank of the Jordan, this was a sign that G–d had rescinded His decree (Numbers 20,12) that he, Moses would not be allowed to lead Israel to the Holy Land. He considered the lands ruled by these kings as part of the land of Israel. Rashi quotes 2,31 where G–d had said: ראה החילותי תת לפניך את סיחון as proof that Moses thought that the decree had been rescinded. If Rashi's reasoning is correct, why did the Torah add the words בעת ההיא "at that time," in 3,23?