I don't know...I get the impression Roger has accepted the racial ideas he was raised with as reasonable and not really thought to challenge them. His line to Bert doesn't necessarily mean that Roger felt strongly about the pov of black people even the way Pete does. It could just be Roger pointing out to Bert that he (Roger) is right in thinking that the government is going to have to give in and give them the law they want. Bert may have thought they could placate them without giving them that, that they didn't really need it.
I think that Roger has accepted the racial ideas that he was raised with as reasonable. But I also think that that line was meant to show that even someone like Roger has the ability to revise his feelings. Given the fact that there were a lot of people who came to recognize that the Civil Rights Law was necessary, who were able to see that the way that they were raised was wrong, I thought it was a nice touch.