Take anything that group says with a grain of salt. David Hogg used the tragedy that happened at that school to try and create a career and line his pockets, the kid pretended to be at the school that day, but wasn't there, but ran to the school after the shooting happened just to jump in front of cameras. He didn't admit to not being there until days later when it got exposed on the internet.
He then proceeded to play victim after he got exposed for always having gun carrying bodyguards with him at all of his anti gun events. He also leveraged a tragedy he wasn't even a part of into a book deal, luckily the book flopped and most recently he leveraged his fame to get accepted into Harvard with only a 1270 SAT when the average score of Harvard admittance is 1520. The piece of shit still claims to have "survived" the shooting, even though he was at his house.
My point being, these people are using fear to push their agenda and personal gain.