I'm not sure what the story is with the times mentioned, I'll leave that for others to figure out.
I can't imagine that if I was hiding in a closet during an attack by a gunman I would be focused on making propaganda videos. Hogg also says that they were having a drill related to active shooters when the shooting started. And then he launches into his gun control pitch for the legislature.
It’s like learning that the 4th plane on 9-11 has been hijacked with the intent of crashing it into a public space as a missile and deciding you’ll film a condescending video decrying the US’s foreign policy in the Middle East instead of going into action to save lives.