A trained, armed-and-ready Black man was right there. He pulled his weapon and fired, but his shots were stopped by the shooter's body armor. Then the shooter fired back with his far more powerful weapon and won the interaction. As usually happens - there's a reason why fewer than 1 in 100 mass shootings are stopped by armed bystanders even in a country where damn near half the population owns a weapon.
Let's say 10,000,000 guns entered the black community in response to this shooting. How many Black lives do you believe would be saved from racist white mass shooters as a result of those 10 million new guns? And on the other side of the ledger, how many of those guns would eventually be used to commit suicide, kill another black person, or be the justification for a cop shooting a black man/woman?