No one deserves to get shot, unless they are engaging in serious criminal acts, or in the process of being apprehended by law enforcement for such acts.
There being no state of war on the ground at the time of the Kent State incident, there is no excuse for firing in an unsafe direction with numerous civilians in the background.
Whether any of those shot were protesters or not is irrelevant. Protesting is nor per se a criminal act, and even if it were, firing on an unarmed crowd doesn't even happen in warfare, let alone police actions.
It reminds me of the Boston Massacre.
Then, as now, the State (in that case, the British) made the case that their soldiers behaved correctly.
Nevertheless, it was the end of careers in the military for a couple of the soldiers who pulled the triggers.
The level of callousness exhibited by some towards the unarmed fallen is quite disturbing, and entirely too deferential towards a (potentially and apparently) Tyrannical State, IMHO.