Johnson, like other presidents, would often reveal his true motivations in asides that the press never picked up.
During one trip, Johnson was discussing his proposed civil rights bill with two governors. Explaining why it was so
important to him, he said it was simple: “I’ll have them niggers voting Democratic for two hundred years.”
“That was the reason he was pushing the bill,” said MacMillan, who was present during the conversation. “Not
because he wanted equality for everyone. It was strictly a political ploy for the Democratic party. He was phony
from the word go.”
- Ronald Kessler, "Inside the White House: The Hidden Lives of the Modern Presidents and the Secrets of the World’s Most Powerful Institution", 1995
So we have on the one hand Caro's (and other historians; see Dallek for example) long detailed account of LBJ and his support for civil rights and other legislation and then on the other you have this anecdote and you think the latter outweighs the former?
As I cited from Caro, LBJ literally risked his presidency - his election in 1964 - by pushing this legislation. His advisers told him no, don't do it, it's too risky, it might split the party, lose the South. But he went ahead. From our advantage point today it didn't appear too risky; but not at that time. They didn't know that a terrible candidate like Goldwater would get the Republican nomination.
He then worked after his election in '64 and after the Civil Rights Bill had been enacted for passage of a Voting Rights Act, a Fair Housing Act, poverty programs, education programs and more to address racial injustice. The civil rights bill alone was enough to secure the black vote. Particularly after Goldwater and the GOP came out against it. Once they did that the black vote was lost for generations. As it has been. So why then follow up with all of this other legislation? It's not needed. He's got the black vote secured.
That long series of acts (yes, he didn't pass them alone; he had a large majority in Congress after the '64 election) are not the acts of a racist who hates black people. If he hated black people then why try to get their vote? And by trying to get their votes in the South he risked losing the larger white vote. And chances for election. Which also happened later. As he said it probably would. It makes no sense.
Was all of this done with no self interest involved? Of course not. He was a mean, nasty, miserable person. Caro documents it - his regular use of the "n" word and other shocking language; as have others. In fact, Caro has repeatedly stated that he "loathes" LBJ. But to dismiss it all - when the evidence presented by Caro indicates otherwise - as being only selfish acts by a racist (really? why would a racist want black votes when he didn't need them? for what) to win over black votes is simply not supported by history.
It's difficult to reconcile these two images: LBJ the user of racist slurs and other horrible language and LBJ the promoter of racial justice. Who was the real LBJ? Answer: both. We have to somehow hold both views of the man at the same time. Not easy to do but it's what he was.