Why did 'Umar ibn al-Khattab call the congregational Tarawih prayer an innovation and yet approve of it?

The Shaykh : However, through induction and following the evidence, we know that a traditional question arises, as they say. If 'Umar did not mean this deviant meaning—that the night prayer in Ramadan behind a single imam was not an innovation after the Messenger (peace and blessings be upon him)—why did we mention his action and statement? Why did he call this prayer an innovation and approve of it? We say that this prayer was left for the duration of the caliphate of Abu Bakr al-Siddiq (may Allah be pleased with him), which, as you know, was about two and a half years, and then for a portion of 'Umar's caliphate, whose exact length Allah knows best, until Allah (Blessed and Exalted is He) inspired him to revive this Sunnah. The reason for the discontinuation of this practice was the circumstances surrounding the caliphate of Abu Bakr, the most important of which, as you know, were the Wars of Apostasy, the preparation of Usamah's army, and other important matters that Abu Bakr insisted on prioritizing over everything to establish a solid foundation for the Muslim state. Then 'Umar came, and time passed, and this prayer was being performed, as we mentioned, without this specific imam. Then Allah opened his heart and inspired him to gather them. Because of this gap and the leaving off of this practice, he called it a bid'ah (religious innovation), meaning linguistically that it occurred after that period of discontinuation. I say that this meaning and this explanation are not from me, but from the great scholars, and I am following them in this. This is not taqlid (following a scholar without knowing his evidence), but following with insight, because no one can ever be ignorant of 'Umar to the point of thinking that he believed the congregational night prayer in Ramadan was an innovation that occurred after the Messenger (peace and blessings be upon him and his family). So, we have invalidated the argument using this report to claim that there is a "good innovation" in the religion, as we have explained the reason for which 'Umar (may Allah be pleased with him) said: "What a good innovation this is". There remains another matter that some may mention.