Guess it depends on your kid. My 17 year (daughter) old (was 13 on 9/11) couldn't watch or listen to anything then. Still can't now. Her sister, one year older (4th day of hs freshman year on 9/11), was mesmerized.
Different emotional make-ups, different way of internalizing the horror. Our next door neighbor was FDNY (with 2 brothers FDNY & NYPD). All safe, thank God, but it was hard watching him leaving in his dress uniform for all the funerals for MONTHS afterwards.
I probably would NOT take a kid. However, for them viewing the movie may not have the emotional impact it does for us, even knowing it was a true story. Five years for a 13 year old is like ancient history.
My son was also a freshman in high school on 9/11. It started him on his road to the Naval Academy. I think it also started a patriotic resurgence, particularly in our youths, that will continue for a long time. At least that's my fervent prayer.