I can’t speak for the others who have cracked wise on this thread, but the reason I’m treating it like a joke is because the idea of an armed guard in a yeshiva is silly and not practial.
Do you really think a terror squad will be discouraged by a semi-retired, bored out of his box, rent-a-cop?
Or should we hire crack staff? (ala Blackwater USA) and who will pay for this?
Or perhaps arm the staff / students, like they do in EY? (yeah, I can just see that taking off here in the USA)
I work in a very “secure” bldg, in NYC and believe me, anyone with a teaspoon of determination could walk trhu the door and wreak havok.
So, when you talk about a school / shul that has a porous border, and people coming and going, we cannot secure the place.
Unless you want to institute an airport like environment (ID, no one admited past a certain point / time) its impossible.
But it is a real danger, so the most commonly used mechanisim to combat an impossible situation kicks in: humor