I've not come across many Muslims willing to actually excuse the large-scale terrorist actions associated with al-Qa'ida; a common reaction is disbelief, which is often interpreted as denial or as being "in denial" and thus unwilling to co-operate. This does not mean Muslims approve; it means that many of us cannot fathom why Muslims would want to do such a thing, hence the tendency to attribute actions like 9/11 and the July 2005 bombings to some conspiracy originating, or wholly existing, outside the Muslim community. They do not just say this to the media or to hostile non-Muslim questioners. By contrast, I have never heard Muslims attributing Hamas suicide bombings to a Jewish conspiracy to make the Palestinians look bad. There are some who approve and some who don't, but the reason why Palestinians would want to kill Israelis is well-understood.
Here's more of that "understanding".