Well, first- the boy he shot wasn't exactly a young child. 13 wasn't he? And there have been examples of serial killers who have targeted both. It is of course a possibility that he is an al Qaeda bad man. But is equally possible that he is a homegrown caucasian American as well- yes or no?
We have threads on this very forum of all manner of sick twisted people and the heinous evil acts they commit. I recall one about a mother who put her baby in the oven and baked it. Sick people, sociopaths come in all forms and stripes. We, in America, have our fair share of them.
A person who would randomly snipe at total strangers for absolutely no discernible reason- well who knows what they would do? Do you? I don't. I do know that this person has targeted adults and children. I do know that other notorious killers have as well.
Other than my own military experience and conversations I have had with people in the past who seemed to have a fetish for sniping- I have no personal experience to draw upon.
I can speculate about the weapon, how he would get into and out of the area and the problems he faced while shooting because these would similar to problems I had been trained to solve.
I can speculate about the white box truck because I used to be the lead man over he assembly line that made this specific model and know those box trucks inside and out.
But I would not kill an innocent person, so I can't tell you what is going through the mind of somebody who would. Everywhere I have ever been on Earth, people seemed to value their children equally well. I see no reason to believe, based upon my scant experience in life, nor from other home grown examples nor from my idle speculation that this person could not easily be a home grown nutter. It could be anybody. But what is there to heavily point to it being a foreign terrorist? I don't see it.