From the news story:
"Officer David Smith was an 18-year veteran of the force, police said at an afternoon news conference.
The suspect, 43-year-old James Clark of Greene, pulled away Smith’s weapon and shot the officer three times, according to police."
By your idiotic argument James Clark was also "unarmed".
"Big" Mike was shot in the hand trying to take the officer's weapon, and then shot dead charging the officer. The officer did what he had to do to go home to his family.