Is it true what the author mentioned: that each of Izz al-Din ibn Abd al-Salam ("Sultan al-Ulama"), Ibn Hajar, Imam al-Nawawi, and Salah al-Din al-Ayyubi were Ash'aris who interpreted attributes allegorically and had flaws in their creed?

The Ash'aris erred in their interpretation of the attributes [of Allah] and deviated from the methodology of the Salaf, to which Imam Abu al-Hasan (definition) al-Ash'ari returned at the end of his life. Therefore, it is not permissible to imitate them in what they erred in. However, the standing of scholars and rulers who agreed with them in some of their errors should not be diminished. Rather, mercy should be invoked upon them, and their books should be benefited from, while avoiding their errors. A Muslim acknowledges the merit of those who possess it, adheres to the Sunnah (definition), asks Allah for guidance to the truth, and frequently researches and presents what they have learned to the sacred texts. A book or author should not be disregarded due to the presence of errors therein, because infallibility belongs to the Book of Allah alone. One who believed in the Ash'ari creed due to imitation, or negligence, or because they were captive to the culture of their era, is excused. For error in some specific matters does not justify abandoning the benefit derived from scholars. Rather, we abandon imitating them in what they differed from the truth. It is a sign of glorifying Allah to honor an elderly Muslim, a حامل القرآن (holder of the Qur'an), and a just ruler. "He is not from us who does not respect our elders, have mercy on our young ones, and acknowledge the right of our scholar." Scholars have consistently strived to weigh good deeds against bad deeds and to judge with justice. And whoever's good deeds are many and great, then what is not tolerated for others may be tolerated for them.