Apparently he was a health and fitness fanatic, very charismatic and was in and out of counselling due to problems with his depression. sound familiar?
Suicide is something people tend to "brush under the rug" and never talk about. By killing himself in this fashion and murdering all the people on the plane his story and plight will be remembered and talked about for quiet some time. He has basically put his own personal reality upon us by force and selfishness.
@Anargyros perhaps not.
How many people suffering from serious depression find themselves in front of a plane? He was just at the wrong place at the right time. Regardless of how we choose to live there is nothing on the other side of oblivion for "good behavior". If he had finally decided to leave this world, end it once and for all, I do not see what reason he would have at that moment in time to show regard for human life. You are ignoring the fact he clocked out of humanities expectations for basic decency the second he locked the security door.
There are also countless stories of people suffering from depression who go on shooting rampages before killing themselves. If you are going against societies rules why not go all out and release your frustration before you die. I would argue that the ones who hang themselves privately were probably 50/50 and good people at the core by comparison, as they at least identified the problem was from within. Both desperately want to escape their pain, but the other lost respect for reality while reaching depression. The loss of respect for others because you believe you were hard done by in life is probably part of what leads people into depression in the first place. Its a domino effect starting with low self esteem and bitterness towards the world and people around you.