A quick peek at history tells us the Alamo was too big to be defended by so few. A big school with a couple guards might be the same problem. Now we're trying to make forts out of schools. Might as well home school and be near our own equiptment.
Poor analogy. We aren't trying to make the schools be forts and we aren't defending each against thousands of combatants. School schools are not trying to capture land or a strategic point. SROs trained to stop shooters are not there to hold the school, but as a deterrent and if that fails, to limit harm as best as possible. Schools are not a seige situation.
Besides, homeschooling would just subject those already in a bad environment to more domestic violence, thereby increasing the odds for childhood injury and death.