The biggest problem with this complaint is that if CA-V is the planet in the goldilocks zone, there has to be more than six planets, a lot more. Our system has three gas giants, for god's sake, and our being in the goldilocks zone is a fluke. If the asteroid belt were a planet our system may not even HAVE a goldilocks zone.
We have four gas giants, or rather, two gas giants (Jupiter and Saturn) and two ice giants (Uranus and Neptune). And Jupiter's gravity is what prohibited the asteroids from coalescing into a planet. Which has nothing to do with the existence of a goldilocks zone, since that's a function of distance from the star.
Also, modern exoplanet discoveries have revealed that the configuration of our system is highly atypical. There are many systems that don't have giant planets, or that have them close to the star, or that have a large number of terrestrial planets spaced close together within less than the radius of Earth's orbit, or have any number of other configurations. There are many factors that can influence the maximum radius at which planets form, planets can migrate to narrower or wider orbits, and outer planets can be jettisoned by close encounters with other stars or the like. So there's nothing to rule out the possibility of a 6-planet system with the fifth being in the continuously habitable zone.
The real problem with the idea of Alpha Ceti having a habitable planet is the same one that applies to other stars in Trek like Rigel, Deneb, Omicron Ceti, etc. -- it's the wrong spectral type. It's a type-III red giant on the asymptotic giant branch of the H-R diagram. Whatever continuously habitable zone it had in its main-sequence lifetime would have moved outward as it expanded into a red giant, so any planets in its current CHZ would not have been there long enough for life to form.
(Some have suggested that "Ceti Alpha" should be considered a distinct star from Alpha Ceti/Menkar, accounting for the discrepancies, but I can see no reason why anyone would give that name to a different star, since it would just create confusion. It's hard to see why anyone would invert "Alpha Ceti" either, but I could see it being the result of some kind of linguistic drift or spacer dialect.)