That’s because it was Dallas...still a conservative area at the time in 1963.
Yes, it was. Adlai Stevenson had supposedly been whacked in the head by a sign carrying enthusiast “US out of the UN”, Adlai being the UN representative. He was reasonably conservative by the Cold War standards of the day, Democrats still being somewhat sane, at least in public.
But the “news” immediately speculated without evidence and blamed a “right wing climate of hate” on the shooting - imagine their distress when it turned out to be a communist defector to the Soviet Union. Not much has changed in 60+ years, just amplified 1000 times and 24/7 now, they don’t even try to hide it.