He doesn't say he participated in designing POSIX in order to devalue AT&T Unix. He says he wanted to come up with a good name for the standard for UNIX-like sy

He doesn't say he participated in designing POSIX in order to devalue AT&T Unix. He says he wanted to come up with a good name for the standard for UNIX-like systems so that people wouldn't just call the standard UNIX. In his view, that would have strengthened AT&T's position relative to other implementations because AT&T held the trademark on UNIX.