The language of the law is clear and the circumstances around resisting "any felony", generally, justify the use of lethal force;
A felony is defined in PC 17 as punishable by death.
PC 196 and 197 both codify instances in which felonious behavior can be legally punished with death.
You can also look no further than article 1 section 1 of the CA constitution for the expressed right to protect property; for instance in the case of FELONY forgery.
A resistor is a victim and witness to an offense that carries substantial penalty (a felony is clearly defined, to this day, in the CA penal code as an offense punishable by death) therefore their life and property is endangered by the criminal actor in both an immediate and sustained condition, if the criminal is allowed to carry out the felony and continue felonious behavior, because the felonious actor risks death in the face of opposition and/or apprehension for the felony.
This argument might not be congruent with the other answers or the court decision the other response referenced, but those instances consist of homicide in resistance to acts that were questionable felonies, perhaps misdemeanors.
In your example, consider a person committing FELONY forgery and not heeding demands to cease the felonious behavior.
Forgery would be considered a felony and not a misdemeanor in instances in which the amount defrauded was greater than $950, or there was a pattern of organized criminal profiteering (for instance) but not necessarily in a single occurrence of petty coupon counterfeiting.
The expression of opposition to the felonious behavior makes the victim a threat to the criminal actor's freedom, interests, and life to the same extent any law enforcement officer would be, but without most of the protections and associations of law enforcement.
In fact, one could reasonably argue that merely being a witness to a felony endangers an individual enough to be justified in homicide, but THAT isn't codified in law.