If it is documented and sourced. Just saying “it came from a book” isn’t enough (Rush Limbaugh was just smeared on alleged racist quotes “from a book” that weren’t documented, and were demonstrably false).
I also would be interested in knowing if Jr. was a registered Republican (I’ve seen no documentation) from the period of 1950-1960 in either AL or GA. Did he vote for Ike or Stevenson in ‘52 if he was registered ? If he did vote for Ike in ‘56, as did Congressman Powell, it may have simply been a one-time situation, before reverting back to usual Dem habits. But as we know, he certainly was no Republican for the ‘60s.
If you have specific evidence the JFK biography (which is a source) is erroneous, feel free to send it to the author and post it here.