A lot of the family members have proven to be jerks in the past dozen or so years. Like this group working with the ACLU against the death penalty:
Or, how about this group which speaks out AGAINST our "torture" of the poor terrorists?
How about the survivors (atheist group) who sued to try and stop having a cross installed at a 9-11 memorial?
How about this family member who is now dedicating her life to defending Muslims and fighting bad perceptions about Muslims?
Sorry, but the scenario the movie depicts isn't outlandish in one bit. Being related to a 9-11 victim didn't make everyone suddenly become pro-American or more sane than they were prior. In fact, that event seems to have given some of these people an excuse for their being and given them "purpose" in life.
But to make a 9/11 victim as a airplane terrorist is reprehensible. It is as reprehensible as making a movie in 1944 with USS Arizona survivors as evil agents of the Japanese.