I agree with you on the involuntary manslaughter
That might or might not change if I had been on the jury.
I had never heard of Z or M until about a week before the verdict. That's how much I pay attention to the media circus.
I suppose it became a hot issue because it involved a black juvenile, a semi-white guy, (I am sure the stirrers would have preferred Z to be lily white),guns, and FL law unpopular with liberals.
A case that should have been routine was turned into an issue that has raised hackles on both sides. One side would like to see bad things happen to Z regardless of what he deserved and the other side is glad to see him get off just to spite the pot stirrers.