A distorted view of history

Pres. Johnson signing the Civil Rights Act, 1964. (Wikimedia Commons)

It's a relatively small thing, it's an American thing, and it's about something that happened 50 years ago.
But it still took only a few minutes for PBS's newest American Experience episode, about the year 1964, to get under my skin, to provoke me to mutter at the screen, and finally to inspire me to turn the program off in protest.
What so bothered me was the section of the show dealing with the U.S. Senate's passage of the historic Civil Rights Act. The episode made the unmistakable assertion that the bill risked defeat at the hands of filibustering Republicans and that it was only when some Republicans ended up being persuaded by Lyndon Johnson to change their minds that the bill became law.
But this assertion set off some alarm bells in my noggin. I know enough about American history of that era to know that Southern Democrats, not Republicans, were the main force against integration and equal rights for African-Americans.
Yes, there must have been some Republicans who opposed the bill and, yes, there must have been some Republicans who changed their minds and ended up supporting it. And those GOP senators may have even been the deciding factor. But surely, I thought, the major opposition to the bill must have come from Southern Democrats--and the PBS show didn't utter a peep about them.
And so I started a bit of online research and it took all of one minute to find this voting record in the Senate on the Civil Rights Act:
Democrats in favour, 46; opposed, 21. Republicans in favour, 27; opposed, 6. Far more Democratic Senators by number (21) and percentage (31%) opposed the civil rights bill than Republicans (6, 18%).
One would have thought that PBS would have found this worth noting. But one would have been wrong.
Perhaps if I had read the online description of the episode, offered on the PBS website, I would have been better prepared to accept the historical distortion it contained. Here's a slice of the "Introduction" the network provided for the show:
"In myriad ways, 1964 was the year when Americans faced choices: between the liberalism of Lyndon Johnson or Barry Goldwater's grassroots conservatism, between support or opposition to the civil rights movement, between an embrace of the emerging counterculture or a defense of traditional values."
Notice how neatly the sentence aligns "liberalism" and a Democratic president with support for civil rights, while at the same time aligning the Republican Party (Goldwater's) with opposition to civil rights? Yes, Goldwater opposed the Civil Rights Act but remember: 82% of Republican senators supported it.
And so, what's the bottom line? Is it more evidence to support the oft-made assertion (by US commentators like Rush Limbaugh and the like) that PBS has a left-wing or liberal bias? Does the big omission tell us something about the sorry state of American culture? Or does it simply make us aware that TV documentary-film makers can make mistakes? I have my suspicions. What are yours?