What is the Islamic ruling on one who claims that Ali ibn Abi Talib was responsible for the killing of Uthman?

Uthman and Ali (may Allah be pleased with them both) were rightly-guided Caliphs. They were companions of the Messenger of Allah (peace be upon him) and both died as martyrs. It is inconceivable that either of them would have conspired to kill the other. Those who killed Uthman (may Allah be pleased with him) were the Kharijites. Ali and his sons defended him, but Uthman insisted that they cease fighting so that Muslim blood would not be shed. It is not authentically reported that any of the Companions were pleased with the killing of Uthman; rather, they detested and loathed it. Ibn Taymiyyah denied that Ali ordered the killing of Uthman, affirming the innocence of both Ali and Uthman from these false suspicions.