That is a comment on the style of C that Bourne used in his shell implementation. He used the pre-processor to e.g. name { BEGIN, } END and do other Algol-isms

That is a comment on the style of C that Bourne used in his shell implementation. He used the pre-processor to e.g. name { BEGIN, } END and do other Algol-isms. Duff would apparently rather read C that was written in C.