It is obvious that you didn't read the post. Of course the 1964 Republicans voted in a higher percentage. The southern democrats, who later changed to the GOP, were the Trent Lotts, and Strom Thurmonds of the era who dominated the South and the Democratic party. The 1964 GOP minority came from the midwest, New England and the pacific northwest and, as a percentage of their number, voted far greater for the 1964 Acts. Look at the subsequent debates, attemped circumlocutions and votes into the early 70s as those southern democrats changed parties.
I read the post. I also lived through that time. Yeah, some southern dems came over. But many racist southern dems stayed put. The GOP STILL is the true party of civil rights.
But they didn't! The only Democratic Senator who voted against the CRA and switched parties was Strom Thurmond. The rest of them remained in the party and in the Senate for many, many years (sometimes, like Stennis, even into the late 80s). I repeat, Strom was the only one.
Another point is that the greatest opposition to the Southern senators who opposed integration was the northern Democratic liberals who had a difficult time breaking the Southern Democratic hold on the agenda. They are not pure, because many of them compromised to maintain their own power. But the Republicans, for the most part, were somewhat passive. Like him or not, it was probably Lyndon Johnson who had more to do with breaking that southern stranglehold on the Civil Rights movement than anyone else. He knew he was most likely turning the south over to the Republicans when he pushed his Civil Rights agenda.