All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
In general, the stated ruling in the other Fatwa is an established unequivocal principle that is supported by authentic texts from the Sunnah. Other incidents in this regard are either inauthentic or took place under certain circumstances that necessitated permitting meeting in seclusion, such as in case of need or necessity.
However, the story of ‘Umar in particular, if it is authentic, it can be understood in the light of being safe from Fitnah and doubts because that woman was old or that his servant accompanied him. Anas said, “After the death of the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, Abu Bakr said to 'Umar, ‘Let us visit Umm Ayman, as the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, used to visit her.’ As we came to her, she wept... ” [Muslim]
In terms of extracting lessons from this Hadeeth, An-Nawawi said, “[It is permissible] for a group of men to visit a righteous woman and to talk to her.”
Allaah Knows best.