Ibn Mas'ud's statement in the hadith of the tashahhud, "Peace be upon the Prophet": Is it a directive from the Prophet or not?

The Shaykh : There is one more point I indicated must be mentioned, which is a benefit in my knowledge that the majority of worshippers have neglected to apply, because this benefit has not reached them, even though it is found in Sahih al-Bukhari and in the Musnad of Imam Ahmad (may Allah have mercy on both of them).
Ibn Mas'ud said, in what we narrated—meaning al-Bukhari and Ahmad with their authentic chains— , he (peace and blessings be upon him) said, . Ibn Mas'ud said, and here is the benefit: We said, , meaning while he was alive and living among his companions. Ibn Mas'ud said, . So Ibn Mas'ud's distinction in saying "Peace be upon the Prophet" in the tashahhud is a distinction based on a directive from the Prophet (peace and blessings be upon him) to him and his companions. The meaning of "directive" is that the Prophet (peace and blessings be upon him) informed them to say "Peace be upon the Prophet" in the tashahhud after his death. And in response to the Prophet's (peace and blessings be upon him) establishing this new legislation for them after his death, they responded to it. So Ibn Mas'ud explicitly stated in this tashahhud that what we said was , meaning they left the form of direct address and moved to the form of third-person reference, saying "Peace be upon the Prophet."
Some of the Shafi'i scholars discussed Ibn Mas'ud's statement: is it a directive from the Prophet (peace and blessings be upon him) or an ijtihad (independent legal reasoning) by Ibn Mas'ud? It was said this and that, but the stronger position is what Imam al-Subki of the Shafi'is mentioned, where he said, "If the statement of Ibn Mas'ud is authentic, then when he died, we said 'Peace be upon the Prophet,' and it became obligatory to shift from the form of direct address, 'Peace be upon you, O Prophet,' to the form of third-person reference, 'Peace be upon the Prophet.'" But the difference between al-Subki's statement and the correction by al-Hafiz Ibn Hajar al-Asqalani is what everyone who heard earlier noted: that this hadith was narrated by al-Bukhari. So al-Subki's statement, "If it is authentic," is a reservation that has no place. Therefore, al-Hafiz Ibn Hajar al-Asqalani corrected him and said, "That is authentic, as it came in the previous narration of al-Bukhari: 'When he died, we said Peace be upon the Prophet.'"
So it is authentic. Second, Ibn Mas'ud did not only report that from himself, but he reported it from the Companions, because he said, "We used to say," not "I used to say." "When he died, we said 'Peace be upon the Prophet.'" Then al-Hafiz Ibn Hajar (may Allah have mercy on him) supported this clear explanation of the distinction between what al-Bukhari narrated with the wording "When he died, we said," not "I said," by supporting this narration with another narration he attributed to the Musannaf of 'Abd al-Razzaq. This book has been printed, praise be to Allah, a few years ago or more. 'Abd al-Razzaq narrated in his Musannaf with an authentic chain from Ata ibn Abi Rabah that he said, "The Companions of the Prophet" . This is an explicit narration: "The Companions of the Prophet (peace and blessings be upon him) used to say during his lifetime, 'Peace be upon you, O Prophet.' When he died, they said, 'Peace be upon the Prophet.'" And so it became obligatory for us to say what his Companions came to say after his death: "Peace be upon the Prophet, and not 'Peace be upon you, O Prophet.'"