Hi,
<Falwell was the liberal's nightmare, the man who launched a thousand Aaron Sorkin plotlines.>
Aaron Sorkin is very famous and good screenwriter....You think his style is 'nightmare'???
//launched a thousand Aaron Sorkin plotlines
What does this mean?
The sentence says that "Falwell was ... the man who launched a thousand Aaron Sorkin plotlines."
Nothing whatsoever is said about the writing style of Sorkin, or of anyone else.
The "nightmare" is Jerry Falwell -- as an influential conservative, he is a "nightmare" for liberals.
Since Aaron Sorkin's plotlines were very often about politics (he was a writer for the television show
The West Wing, which was about politicians), a famous conservative who was politically influential would have been the source of many stories Sorkin wrote -- that is to say,
Falwell launched many of Sorkin's plotlines.