Mental issues or no, committing suicide in a crowded place where there are children and families and, in general, anyone halfway sensitive, is indefensible.
One may say that the act has an intrinsic selfishness to it, yet there are ways to kill oneself that minimize the suffering of those who discover your body. I have considered this a lot and think that there is are definitely ways to kill yourself and reduce the amount of people who will be traumatised by your actions.
I understand why he did it, because when you suffer from these issues - suicide is a default setting, the thoughts never go away and you seriously begin considering it as a response to trivial, meaningless things.
Yet I maintain he did it in the wrong way. I hope those who saw it can get over what he did to them.