The SC has already ruled that LEO have no obligation to "protect".
This case will go nowhere.
Might, might not. The case you're referring to was a different set of circumstances. Sickening that it happened, but different. The case you're referring to was a home invasion/sexual assault. SCOTUS ruled that law enforcement had no duty to protect any one individual.
This is not one individual and this wasn't about Patrol response, this is about a mass shooting and a site-dedicated LE person fully equipped and capable (minus one thing, a spine) of engaging the shooter not doing what he was already on the premises to do.
Ed