I think Farook got pissed at his Jew co-worker and jumped the gun on the attack. Not sure this facility was even in the plan, why would it be.
I've speculated along those lines myself - maybe Farook let emotions get the better of him, to the detriment of what looked like a much bigger plan - mixing personal issues with business is just bad juju. They'll birddog you quick, which is what happened within thirty minutes of the attack. The flipside of that is what if this was deliberately in a plan as the first hit of many to come - still dumb as hell. Either way, Farooky boy's reckless strategy may have actually saved lives in the long run.
30 minutes is forever. There was a police officer on his lunch break that responded first. Took him 7 minutes to get on scene. Still too long, and the guy is a hero - no two ways about it.
Attacking an armed terrorist with a stapler is STUPID, when it is more effective to attack him with YOUR PERSONAL FIREARM - THE ONE THE CONSTITUTION GUARANTEES YOU ARE ALLOWED TO CARRY WITH YOU AT ALL TIMES.
Four people with pistols probably would have saved 20 people.