To be fair, and I really hate agreeing with wannabee fascist trash like Trump’s entourage; it is very surprising a roof top, at most 250 yards from the stage, was not secured.
Your point still stands though, they do not give a shit about school shootings, or anyone who isn’t a means to more power/money for themselves.
It looks like a pretty typical windshield, except mounted close to vertical. Last I knew the USPS was running at a profit, except for the bribed politicians making it a law they need to fund pensions way into the future, that is.