Is it true that Ibn Hazm's view is that Abd al-Rahman ibn Muljam only killed Ali (may Allah be pleased with him) as an interpreter and a mujtahid, and believing himself to be in the right?

The text mentioned by Ibn Hazm in "Al-Muhalla" discusses the argumentation of the Hanafis and Malikis for the killing of Abd al-Rahman ibn Muljam by Al-Hasan (definition) ibn Ali, to prove the permissibility for an adult to demand retribution (qisas) without waiting for a minor to reach maturity. Ibn Hazm, while agreeing with the ruling, criticizes their argumentation, pointing out that they do not consider retribution for killing based on interpretation (ta'wil), and this applies to Ibn Muljam's act.

Ibn Hazm describes the Khawarij, including Ibn Muljam, as "interpreters (mutawwilun), diligent (mujtahidun) who believe they are guided," despite the corruption of their interpretation. He supports this with evidence, including: 1. The Hadith (definition) of Dhul-Khuwaysira Al-Yamani, who described the Prophet (peace be upon him) and his companions as saying: "They recite the Qur'an but it does not go beyond their collarbones; they will pass through Islam as an arrow passes through its target." 2. The interpretation of the verse: (Say, "Shall We inform you of the greatest losers in [their] deeds? [They are] those whose effort is lost in worldly life, while they think that they are doing good work.") where Ibn Kathir stated that it includes the Khawarij and those who worship Allah in a way that is not pleasing. 3. The declaration of the Khawarij that killing Ali (may Allah be pleased with him) was an act of closeness (qurbah) to Allah, exemplified by the poetry of Imran ibn Hattan: "O blow from a pious one, he intended nothing by it but to attain the pleasure of the Lord of the Throne."

Thus, the Khawarij, including Ibn Muljam, think they are on guidance, while they are misguided and deviant from the religion.