Praise be to Allaah.
We put this question to Shaykh Muhammad ibn Saalih al-‘Uthaymeen, may Allaah preserve him, who replied as follows:
“If he does not call others to follow his bid’ah and is not stubborn when the truth becomes clear to him, there is nothing wrong with him leading the prayer, otherwise, it is better if someone else leads the prayer even if he knows less Qur’an. And Allaah knows best.”
Sheikh Muhammed Salih Al-Munajjid