Tirmidhi

Hadith Commentary:
From this, it is clearly understood that the Sunnah method after the obligatory prayer is that, after saying the salam, the imam should turn his face to the right or left and sit facing the congregation. But, alas, a Deobandi translator and commentator of Bukhari states: "Nowadays, it is common practice to sit turning to the right or left, but there is no basis for this; it is neither Sunnah nor recommended, though it is certainly permissible." (Tafheem al-Bukhari, vol. 4, p. 22)

Then what is the meaning of the mentioned hadith and the chapter established upon it? The answer given by the aforementioned scholar is that the author (rahimahullah) wants to clarify that after finishing the prayer, if the imam wishes to go home, he may do so; but if he wishes to remain in the mosque, then the Sunnah is that he should sit facing the other people present. (Reference as above)

Readers themselves can judge how much contradiction there is between both statements of the esteemed commentator of Bukhari.
The meaning of the chapter of Imam Bukhari (rahimahullah) and the hadith is clear.

Hadith Commentary:
(1)
In this hadith, the blessed habit of the Messenger of Allah (sallallahu alayhi wa sallam) is described: after completing the prayer, he would turn his face towards the congregation (muqtadis).
The commentators have mentioned the wisdom behind this as follows: so that someone coming from outside would know that the congregational prayer has already been performed.
If the imam were to remain seated facing the qiblah, there could be a suspicion that perhaps he is still sitting in the tashahhud.
Another wisdom mentioned is that the imam may teach the congregation matters they are in need of, or give them admonition and advice.
(2)
Allamah Zayn ibn al-Munir writes that the imam turning his back to the congregation was due to the requirement of leading the prayer; once the prayer is completed, this reason also ceases. Since he is now free from the responsibility of imamate, the imam should sit facing the congregation. By doing so, there will be no suspicion of arrogance, pride, or superiority over the congregation.
In any case, the imam should, after completing the prayer, sit facing the congregation rather than turning his back to them; this was the blessed habit of the Messenger of Allah (sallallahu alayhi wa sallam).
If there is a need, he may, after the salam, immediately go to fulfill his need, as will be mentioned later.
(Fath al-Bari: 2/431)

Hadith Commentary: Benefits and Issues: This hadith establishes that the imam should sit facing the congregation after the dawn (Fajr) prayer, and if the followers have anything to ask, they should do so. It is more appropriate to interpret dreams after the dawn prayer, because the dream is still fresh in the mind of the one who saw it, and the interpreter’s mind and intellect are present and attentive; he has not yet become preoccupied with concerns of livelihood. Therefore, the opinion of those who say that one should not ask for the interpretation of a dream before sunrise is incorrect.