I think that's tied to how Democrats/progressives have been collectively gaslighting themselves over the 2020 "Summer of Love".
They romanticized those BLM chimpouts to an insane degree as "the heroic civil rights struggle of our time", and any facts that were inconvenient to that self-serving narrative were aggressively blocked out.
"It was just peaceful protests!
And Antifa is just a right-wing myth!
Or if not, then reports of their violence and destruction must be greatly exaggerated!
Or if not, then White Supremacist™ instigators must have provoked it and are thus to blame!"
Deep denial.
So the way Rittenhouse was being friendly and peaceful and helpful all evening, until he was chased and attacked by those three violent White dindus - that just doesn't fit into the narrative. They can't fathom it.
No, by standing against the "mostly peaceful protesters", Kyle stood against the very civil rights struggle itself!
He was essentially a 1965 cop opening fire on MLK's march over the bridge in Selma!
A 1945 Wehrmacht soldier launching one last attack against allied forces to prevent them from freeing a concentration camp!
Kyle made a stand against the "right side of history", against the "long arc of justice".
That's the only possible way to think of his presence in Kenosha that night - the narrative allows no other.
And that's why leftoids need no other reason to convict Kyle than
"He was there. He should not have been there!"
Luckily, it's unlikely that all 12 final jurors will be leftoid NPCs.