I guess the prudent thing would be to ascertain what's going on and not just immediately open fire when the door comes down, given the fact that police are the one group in our society most associated with battering ram door entries. One might want to at least consider that it may be police, if you honestly don't hear them calling out "police! police!" as they did here.
On top of this, this wasn't exactly some 65 year old white couple in rural Vermont in their farm house, winding down a lifetime of near-zero criminal activity, and their door suddenly comes crashing down as intruders come in. This was an apartment rented by a woman who had been involved in drug dealing and at a minimum assisting a drug dealer in movement of drugs and funds, etc. I strongly suspect Kenny, the boyfriend who opened fire, had some familiarity with the concept that police might be interested in Breonna, in Jamarcus, in the apartment. I wouldn't be very surprised at all if he himself had had run ins with the law too.
So I think it's not unreasonable to ask that "could this be the cops?" should have been at least on his radar, enough to not start opening fire instantly.
If you want to say that was reasonable for him to do, then okay... but then it doesn't change the fact that the cops firing back was even more reasonable. Then executed a lawful warrant on a drug connected house and one of them was shot as they entered. Should they not have returned fire?
On one hand we're told that blacks live in constant fear of police attention, but then I'm supposed to entertain the idea that Kenny and Breonna had no concept that it might be the police at the door?
I believe in the press conference today they said they had not been able to ascertain which officer's gun was responsible for the fatal round that hit her. Though I don't think that was the primary reason for not charging those two officers.