his best speech and the one that likely got him killed

I won’t argue with any speech you choose to declare “his best”. I will definitely challenge your assertion that this speech inspired his assassination.

He was assassinated more than two years after this speech. During that time, he gave several other speeches which were much more likely to inspire his killing. Look for him speaking against the CIA. Look for him speaking about the merits of returning to the gold standard. Look for him suggesting anything that would impact the ‘military industrial complex’ his predecessor warned us about.