One of our values is that certain things are unforgivable. Some acts can never be justified or tolerated, and it is wrong to even attempt to justify them or even consider their motivation, let alone to act to remove the grievances of those who committed such unforgivable acts.Many acts may be unforgivable, but to use that as an excuse for ignorance... feh. How can one understand why an act is evil if one refuses to comprehend all the facets of it, including motive?
Then again, when someone says "All those who grieve for our dead but... share no important values with us", they will obviously brook no disagreement, no matter how (Iraq) valid (squelching of speech) the questions (unilateralism) can be (Homeland security). What's worse, exactly.. perceived sympathy with killers, or using the deaths of their victims as an excuse to shame others into cowed silence?
And why should anybody have to make that choice?