I studied comets, and published some original research on comet tail interaction with the solar wind, not that my opinion matters much, but in my experience for what most researchers classify comets, this is absolutely a megacomet. It's more than twice as large as the one I kept in my mind from a decade ago that I considered one of the larger comets and Humason [0] was only about 40km in diameter.
Yes, cold bodies that have the properties of a comet may have lived the life of a comet at some point, or will again in the future, but currently something that shares a common center of mass with another object in a pretty stable orbit is not really going to get the full comet red carpet at the comet awards :)
2060 Chiron /ˈkaɪərɒn/ is a small Solar System body in the outer Solar System, orbiting the Sun between Saturn and Uranus. Discovered in 1977 by Charles Kowal, it was the first-identified member of a new class of objects now known as centaurs—bodies orbiting between the asteroid belt and the Kuiper belt.
In Greek mythology, Chiron (/ˈkaɪrən/ KY-rən; also Cheiron or Kheiron; Ancient Greek: Χείρων means 'hand') was held to be the superlative centaur amongst his brethren since he was called the "wisest and justest of all the centaurs".
Chiron – A centaur with a white stallion body[9] and a son of Kronos. He is the mentor of Percy Jackson and the activities director at Camp Half-Blood. In The Lightning Thief, he first appears, disguised as a Latin teacher at Percy's school. He uses an enchanted wheelchair to conceal his horse half.[7] Chiron is played by Pierce Brosnan in the first film and by Anthony Head in the second film. In the musical, he is portrayed by Jonathan Raviv.
Also, it's fair to say systems based on classification based on subjective criteria will always have grey area, so any absolute statement about them will be difficult to defend :)
