The holding in Garner is the following:
The Tennessee statute is unconstitutional insofar as it authorizes the use of deadly force against, as in this case, an apparently unarmed, nondangerous fleeing suspect; such force may not be used unless necessary to prevent the escape and the officer has probable cause to believe that the suspect poses a significant threat of death or serious physical injury to the officer or others. Pp. 497 U. S. 7-22.
Nothing about “imminent” and nothing about “objective.” So scratch “imminent” and replace “objective” with “probable cause to believe”. Just sayin...
“The use of deadly force to prevent the escape of all felony suspects, whatever the circumstances, is constitutionally unreasonable. It is not better that all felony suspects die than that they escape. Where the suspect poses no immediate threat to the officer and no threat to others, the harm resulting from failing to apprehend him does not justify the use of deadly force to do so. It is no doubt unfortunate when a suspect who is in sight escapes, but the fact that the police arrive a little late or are a little slower afoot does not always justify killing the suspect. A police officer may not seize an unarmed, non-dangerous suspect by shooting him dead. The Tennessee statute is unconstitutional insofar as it authorizes the use of deadly force against such fleeing suspects.”
“For accreditation by the Commission on Accreditation for Law Enforcement Agencies, a department must restrict the use of deadly force to situations where “the officer reasonably believes that the action is in defense of human life . . . or in defense of any person in immediate danger of serious physical injury.” Commission on Accreditation for Law Enforcement Agencies, Inc., Standards for Law Enforcement Agencies 1-2 (1983) (italics deleted)
Immediate and imminent are interchangeable terms in law and whenever there is a reference to “reasonable” means objective reasonableness.