Political speechwriters are often simply hired professional wordsmiths who'll work for anyone who pays them. There are plenty of political speechwriters who've worked for people they totally disagree with. Then there are the speech writers who'll write on certain topics but not others. For example, Governor Maddox had strong opinions on many subjects. Even people who disagreed with him about his views on integration might agree with his stand on taxation, or on road building.
Since you didn't post any link to an information source that verifies your assertion, and you didn't provide any details about where, when, and how much Boortz wrote for Maddox, your launch post question doesn't provide much to talk about or comment on.
Was Boortz a permanent staff writer, or was he hired as a freelancer to do piece work? When did Boortz work for Maddox, and for how long? Are there any examples available of the actual speeches themselves?
I once sold a speech to a local township supervisor when I was in high school. He needed a five minute speech for a dedication of a new local park ceremony, and my English teacher suggested me to the supervisor's secretary. I made a quick $50, which in the 1960's was a pretty good deal for a teenager. The speech was just a bunch of cliches and platitudes about how parks were for children, and being for children is good. I'd hate to discover that the supervisor went on to be elected to higher office and turned out to be some jerk and I'd have my name associated with his because of a quick speech I wrote over 40 years ago.