I own a security guard company. Our guards carry OC/Baton/Taser and some handgun. OC/Taser are considered 'less-than-lethal' as is Baton GENERALLY (depending on strike points). I said this because I've been certified in all of the devices listed above:
OC can incapacitate you enough to have your weapon taken away.
Baton IMO is DEADLY force, IE: Someone gets hold of my baton and doesn't follow verbal commands (and there is no where to run..not required but i'd run..) I'd likely employ deadly force.
Taser - We just ordered new X26's and prior had M26's I can attest that these devices are extremely effective at incapacitating someone. Especially the NON-L.E models which give a 30 second firing.
To answer your question: If speaking clearly within the boundary's of the law my state says that
DEADLY FORCE IS NEVER CONSIDERED JUSTIFIED IN RESPONSE TO A NON-DEADLY THREAT.
I'm not sure if one would be able to articulate how they felt the threat was deadly based on 'what-could' happen after the initial battery.
In short I agree with ISLANDER.
Quick to the gun, Sure of your grip. Quick to the threat, sure of your shot. - Chris Costa