If the cops directly shot the child without there being the presence of a firearm near the child, then that would be a fairly different conversation. And yeah, the parent comment may have assumed the “good guy with the gun” was not a cop, but instead a citizen. However, with these being cops, and their decision to shoot spawning from a citizen with a firearm who had intent to use that firearm to harm innocent people, it is still valid for there to be a gun control debate, because if you take her gun out of the equation, there likely was not going to be a police initiated shooting in this situation.
The whole right wing has a perpetual sedition boner.