"It was not our intention to create an image resembling the attacks... nor did we see the resemblance during the design process," but "I have to admit that we also thought of the 9/11 attacks."
ADDED: Assume the architects intended to allude to the 9/11 image. Why would they do that? It can't be to give offense! Why would that be effective, to refer to 9/11 as if you were happy about it? If this building deliberately evokes the WTC in a state of destruction, it can't be to approve of the destruction, because the architects must want people to love their building. The point would need to be something more like: We defy the terrorists of the world. We stand for building skyscrapers in defiance of the nihilists.
Negative images can be adopted and re-purposed in a positive way. To cite an obvious example: the crucifixion of Christ. A crucifix is not displayed celebrate the torture and execution of Jesus. We invariably and easily understand it as a symbol of resurrection and eternal life.
So the building, if it indeed intentionally refers to the WTC, should be interpreted as a reaffirmation of the greatness of modern civilization.