Someone said the irony is that a lot of synagogues already have armed guards because they constantly get threats from Neo-nazis, or who Trump refers to as very fine people.
The reality is that, most armed guards are either people at the twilight years of their career, and maybe life, or doing it just for the paycheck. To be honest, most people, even experienced police officers are probably not going to be John Wick when a guy who has a death wish and not really afraid of dying comes in with semi-automatic weapons with a massacre in mind and sometimes explosives and just start shooting. Most people aren't mentally prepared to get into a firefight everyday. In that scenario, its more likely the attacker is going to have the upper hand. They probably going to shoot the guards first before they shoot anyone else and he is most likely going to have the advantage by being on the attack first.