I didn’t read it as Q claiming the act itself was a false flag but rather the immediate gathering of teens on tv and in the streets with big money flying in faster than the families could even grieve.
It, the aftermath, was most assuredly planned.
I think Q is referring to the circus in the aftermath.
Although if an actual false flag shooting, iron-clad proof would be necessary.
There is so much about Parkland that doesn’t make any sense, disagrees with itself, and so on, that the very best that can be said about it is “they let it happen”.