FrogNog, //opinion polls are just that, opinion.//
They are indeed, and in the opinion of a considerable number of Muslims worldwide, Islamic terrorism is justifiable.
//Why should they distance themselves from anything when they have done nothing to be ashamed of?//
This answers your question.
http://www.heraldscotland.com/news/home-news/young-uk-muslims-in-protest-at-islamic-terrorists.25351681
//muslims should not speak out to defend their lifestyles because they are doing nothing wrong.//
Thankfully some of them disagree with you.
http://www.activechangefoundation.org/portfolio-item/notinmyname/