It was the robots. The godamn ROBOTS. (Well, possibly)
1. In Akea there is obvious human/robot tension with Ribateau talking about humans paying for the enslavement of robots and Liam saying if he can build robots, he can destroy them.
2. Perhaps if the robots provided the materials for Gambino's tower they could have easily sabotaged it, causing the collapse
3. Bots are outlawed in Gaia. Could this be hinting towards conflict in the past?
If the animosity is as strong as I believe it to be, then the robots have sought to take over Gaia by destroying its two most powerful parties: Gambino and the Von Helsons.
The shooting and the falling tower was two birds with one stone.
What do you think?