I don't know who these people associate with, but I have seen a lot of Muslims and liberals addressing extremism, the problem we all have is grouping all Muslims into this group.
Someone mentioned Bill Maher in another thread and I saw a youtube interview he had with Asra Q Nomani and extremist Muslims was the topic.
Reza Aslan also discusses the issues on cable TV.
I discussed the Wahhabist at length during the lead up to the Iraq war and that no one seems to mind the Saudis, Emirates or other who had oil and their human rights issues or their financing questionable organizations and people.
Liberals talk about Islam, but we don't group them all together and we know there is a problem, but it is the extremist, as it is in every ism, that are the rebels, the zealots and those who aren't live and let live types of people that cause the terror, not those who are just trying to go about living their lives, like you and I.