Is the book "Al-Farq bayn al-Firaq" by Abd al-Qahir al-Baghdadi consistent with the methodology of Ahl al-Sunnah wal Jama'ah?

Al-Baghdadi was an Ash'ari in madhhab (school of thought), and this is evident from his biographers' attribution of this to him, his presentation of the Ash'ari creed as the creed of the saved sect (al-firqa al-najiyah), and his authorship of the book "Usul al-Din" (Foundations of Religion) in the manner of the mutakallimun (scholastic theologians) and the Ash'ari madhhab. His methodology in the book "Al-Farq bayn al-Firaq" (The Differences Between the Sects) relied on the hadith of disunity, classifying the Islamic sects, and presenting the views of the sects by making their proponents foundational figures. His book was distinguished by its excellent organization and began with introductions on disagreements and disunity. He limited himself to presenting the views of Islamic sects, agreed with Al-Ash'ari in counting the foundational principles of the sects, and presented Ash'arism as the correct creed. His presentation of the sects was comprehensive, and he followed a methodology of reporting and criticism, discussing the views of the sects with a harshness that sometimes reached the point of insult and declaring them disbelievers.