What an utterly ridiculous statement.
The entire premise of this article is one of the oldest motives for violence in the history of the human race.
Or did you somehow think this was the first middle eastern child killed by America?
Analogy: a wasps best appears on your porch. Occasionally, you get stung.
Do you a) put up with being stung once in a while or b) whack the ever living shit out of the nest with a stick, knowing retaliation is the likely outcome, and wait to see what happens?
In spite of what the US media liked to portray, OBL was an intelligent man, well versed in both war and politics.
So no, there is no motive, unless you're suggesting that OBL's goal was to get Afghanistan and Iraq invaded, and millions of Arabs killed?
"[It is] easy for us to provoke and bait this administration. All that we have to do is to send two mujahidin to the furthest point east to raise a piece of cloth on which is written al-Qaeda, in order to make the generals race there and cause America to suffer human, economic, and political losses ... This is in addition to our having experience in using guerrilla warfare and the war of attrition to fight tyrannical superpowers, as we, alongside the mujahidin, bled Russia for 10 years, until it went bankrupt and was forced to withdraw in defeat." - OBL, 2004
So yes, it's very fair to suggest that his goal was to get Afganistan and Iraq invaded given that his formative years were spent, in his mind, bringing down the Soviet Union by provoking them into a protracted and costly battle in Afganistan. Al Queda is responsible for killing thousands of Arabs directly. It's no stretch to think that he didn't mind seeing a few million killed, like all sorts of utopian-totalitarian ideologues who preceded him, in the cause of bringing about 1000 years of utopia on earth through the establishment of a new Caliphate.
OBL was an intelligent man, like Hitler or Stalin were intelligent men. Ruthless, but almost impossibly warped in his views on why the present he lived in didn't fit his own fantasy.
"It is enough to know that the economy of all Arab countries is weaker than the economy of one country that had once been part of our world when we used to truly adhere to Islam. That country is the lost Al Andalus... No Muslim territory should ever become non-Muslim...Let the whole world know that we shall never accept the tragedy of Andalusia." - OBL, 2004
There's your motive if you're looking for one. Spain defeated the Muslim invaders who had conquered part of it 500 years ago and since it's now richer than the whole Muslim world put together it proves that... wait... what?
Again, why break the habit of a lifetime?
"Live and let live" is a concept which no longer seems to be part of popular cognition.
And the analogy still holds.