The MAIN reason for the FF shootings is the Gun Grab. It starts out as gun control and then escalates from there. The bills they want to pass will have a hidden agenda like the one they wanted to pass after the Vegas shooting:

"New Bipartisan Bump Stock Bill Would Actually Ban All Semi-Automatic Rifles"

thefederalist.com/2017/10/13/new-bipartisan-bump-stock-bill-would-actually-ban-all-semi-automatic-weapons/

Secondly they want to create chaos, discord, and CONFUSION.

The whole Hogg yearbook tweet reeks of a CNN "trick". In order to make the conspiracy theory look senseless they put out the California yearbook tweet and once they made that viral they put out the Florida yearbook video tweet debunking the Laguna Antifa tweet. It's purely psychological the way they try to play both sides.