The Jargon File (version 4.4.7, 29 Dec 2003):

Unix conspiracy
 n.

    [ITS] According to a conspiracy theory long popular among ITS and 
    TOPS-20 fans, Unix's growth is the result of a plot, hatched during the
    1970s at Bell Labs, whose intent was to hobble AT&T's competitors by making
    them dependent upon a system whose future evolution was to be under AT&T's
    control. This would be accomplished by disseminating an operating system
    that is apparently inexpensive and easily portable, but also relatively
    unreliable and insecure (so as to require continuing upgrades from AT&T).
    This theory was lent a substantial impetus in 1984 by the paper referenced
    in the back door entry.

    In this view, Unix was designed to be one of the first computer viruses
    (see virus) ? but a virus spread to computers indirectly by people and
    market forces, rather than directly through disks and networks. Adherents
    of this ?Unix virus? theory like to cite the fact that the well-known
    quotation ?Unix is snake oil? was uttered by DEC president Kenneth Olsen
    shortly before DEC began actively promoting its own family of Unix
    workstations. (Olsen now claims to have been misquoted.)

    If there was ever such a conspiracy, it got thoroughly out of the plotters'
    control after 1990. AT&T sold its Unix operation to Novell around the same
    time Linux and other free-Unix distributions were beginning to make
    noise.


The Free On-line Dictionary of Computing (30 December 2018):

Unix conspiracy

   [ITS] According to a conspiracy theory long popular among
   ITS and TOPS-20 fans, Unix's growth is the result of a
   plot, hatched during the 1970s at Bell Labs, whose intent was
   to hobble AT&T's competitors by making them dependent upon a
   system whose future evolution was to be under AT&T's control.
   This would be accomplished by disseminating an operating
   system that is apparently inexpensive and easily portable, but
   also relatively unreliable and insecure (so as to require
   continuing upgrades from AT&T).  This theory was lent a
   substantial impetus in 1984 by the paper referenced in the
   back door entry.

   In this view, Unix was designed to be one of the first
   computer viruses (see virus) - but a virus spread to
   computers indirectly by people and market forces, rather than
   directly through disks and networks.  Adherents of this "Unix
   virus" theory like to cite the fact that the well-known
   quotation "Unix is snake oil" was uttered by DEC president
   Kenneth Olsen shortly before DEC began actively promoting its
   own family of Unix workstations.  (Olsen now claims to have
   been misquoted.)