Why did 'Umar ibn al-Khattab (may Allah be pleased with him) call the congregational Tarawih prayer an innovation and yet approve of it?

The Shaykh : However, we know through induction and following the evidence that a traditional question arises here, as they say. If 'Umar did not mean this deviant meaning—that the night prayer in Ramadan, performed in congregation behind a single imam, is not an innovation introduced after the Messenger (peace be upon him)—given the actions and words we mentioned, then why did he call this prayer an innovation and approve of it?
We say: This is because 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, the length of which Allah knows best, until Allah (Blessed and Exalted is He) inspired him to revive this Sunnah. Due to the interruption of this Sunnah because of the circumstances surrounding 'Umar's caliphate, the most important of which, as you know, were the wars of apostasy and the preparation of Usamah's army, and similar important matters that Abu Bakr insisted on prioritizing over everything to establish a solid foundation for the Muslim state. Then 'Umar came, and the time that had passed passed over him, 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 this abandonment of the practice of this Sunnah, they called it a bid'ah (religious innovation); that is, a bid'ah in the linguistic sense, meaning that it occurred after that abandonment.
I say: This meaning and this explanation are, first of all, not from me, but from the great scholars, and I am following them in this, not as taqlid (following a scholar without knowing his evidence), but as following with insight. Because no one can ever consider 'Umar ignorant 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). Thus, we have refuted the use of this report as evidence that there is a good bid'ah (religious innovation) in the religion, as we have explained the reason for which 'Umar (may Allah be pleased with him) said: "What a good bid'ah this is."