Seems a stretch, the civil rights bill was JFK’s baby initially, and if JBJ hadn’t been president it’s pretty likely that another democratic president would have signed it, possibly Humphrey or McCarthy.
The book "master of the senate" makes a pretty compelling case against this. LBJ was a masterclass politician (honestly much better than JFK or Humphrey). It makes the point that basically every liberal president since the Civil War had tried to pass some sort of civil rights bill only for it to fail
Nah election fraud matters pretty materially. If it werent for this rigged election, we would have never gotten the 1964 civil rights bill
https://en.wikipedia.org/wiki/Box_13_scandal