"The very existence of controversial material in Muhammad’s life story means any public representation of his life and character is going to be selective. It will either include offensive material and become polemical in nature, or it will censor it and risk becoming nothing more than propaganda. This is a serious practical difficulty for non-Muslims who wish to study and critique Islamic canonical texts. When primary historical source traditions about Muhammad are made known, ordinary Muslims can react with shock, denial and anger, because they are not comprehensively educated in the realities of Muhammad’s life and are unable to process this confronting material as a truthful report. An example of this was the conviction in 2001 of Pakistani Christian school principal Pervaiz Masih of blasphemy, apparently for referring to Muhammad’s marriage to Aisha when she was six, and saying –as is indeed the case –that this is recorded in the Sahih al-Bukhari.[19] Masih was acquitted on appeal in 2006, after five years in detention." -- from The Third Choice by Mark Durie
Most Muslims are like most westerners. They are honest people. But there is an important difference; they’ve been told from their infancy that Muhammad was a perfect man. So it’s only natural that they defend him when they hear someone criticise something he said or did.
For this man's story see here.
The Quran, the Bible, and the Islamic Dilemma