Lets not be selective when you cite something.
§ 9.41. PROTECTION OF ONE'S OWN PROPERTY. (a) A person
in lawful possession of land or tangible, movable property is
justified in using force against another when and to the degree the
actor reasonably believes the force is immediately necessary to
prevent or terminate the other's trespass on the land or unlawful
interference with the property.
(b) A person unlawfully dispossessed of land or tangible,
movable property by another is justified in using force against the
other when and to the degree the actor reasonably believes the force
is immediately necessary to reenter the land or recover the
property if the actor uses the force immediately or in fresh pursuit
after the dispossession and:
(1) the actor reasonably believes the other had no
claim of right when he dispossessed the actor; or
(2) the other accomplished the dispossession by using
force, threat, or fraud against the actor.
There are degrees of force. One must use reasonable force. If one is not justified in using deadly force, then they have used excessive force.
In addition, as I and others have repeatedly pointed out, once a suspect is handcuffed and restrained, the arresting person has custody of the suspect and is responsible for their wellbeing. You can not restrain someone and then shoot them, which is essentially what happened here.