The important message here is "Don't go pointing a gun at someone else unless you are willing to be shot by them."
Point an AK at me I take that as an imminent threat of severe bodily injury or death.
The man's response was appropriate.
What was not appropriate was the DA instructing detectives to omit Brady Material (exculpatory information) from their submissions to the grand jury.
IMHO, there would have been no indictment had that material been present.
Withholding Brady Material is unconstitutional, and to collude (conspire) to do so a violation of the accused's rights to Due Process under the Law.
Conspiracy to deprive someone of one or more Civil Rights under color of law is punishable under Untied States' law:
18 U.S.C. § 242
Whoever, under color of any law, statute, ordinance, regulation, or custom, willfully subjects any person in any State, Territory, Commonwealth, Possession, or District to the deprivation of any rights, privileges, or immunities secured or protected by the Constitution or laws of the United States, or to different punishments, pains, or penalties, on account of such person being an alien, or by reason of his color, or race, than are prescribed for the punishment of citizens, shall be fined under this title or imprisoned not more than one year, or both; and if bodily injury results from the acts committed in violation of this section or if such acts include the use, attempted use, or threatened use of a dangerous weapon, explosives, or fire, shall be fined under this title or imprisoned not more than ten years, or both; and if death results from the acts committed in violation of this section or if such acts include kidnapping or an attempt to kidnap, aggravated sexual abuse, or an attempt to commit aggravated sexual abuse, or an attempt to kill, shall be fined under this title, or imprisoned for any term of years or for life, or both, or may be sentenced to death.
This may call for a pardon of the man convicted, but it calls for prosecutions as well for the DA who 'requested' Brady Material be left out of investigator's reports and possibly for the investigator(s) as well. Of course, if they came forth and indicated they were under duress, perhaps the investigators could be granted immunity...