Did Ky commit the crime? Yes, in self defence (according to him).
Should he have to face responsibility for the loss of human life? yes.
Should someone have to spend 20 years in prison for self defence (again, allegedly, I know very little about this case)? no, especially if there are no violent priors.
Black trans people live incredibly dangerous existences. trans women of colour, for example, have a 1 in 8 chance of being murdered. Being a black trans man doesn't suddenly make your life any easier (though I don't have specific numbers for trans men), and as you being to pass as a man, it means you inherit the way that society treats black men (i.e. poorly).