I imagine that he had very little activity on it as there were very few links.
However, I bet law enforcement and Twitter took the page down so it would not be added to or hacked.
A familiar pattern is emerging in these events, in which the public quickly tries to find scraps of information about the perps on the Internet to try to find out who they are and who they are connected to before the authorities can clamp down and wipe the social media pages and declare it a "lone wolf" or "workplace violence."