Chiron was discovered in (I think 1977) and I believe that its Astronomical designation has changed on more than one occasion. However a large number of Astrologers use it (though I tend not to - mainly because I have enough to handle with the other planets).
The first problem with Chiron as a ruler is the question of whether it's a planet (I think the Astronomical view is that it is not). The vast majority of Astrologers, whether traditional or modern allocate rulership to planets rather than centaur bodies, or asteroids. The second is what is the basis for allocating rulerships.
I think your namesake, Lee Lehman distinguised two types of rulership. The first is one by association or correspondence. Thus, for example, Mars rules accidents, and Saturn rules the skeletal system, Pluto rules mineshafts and either Mercury or Uranus (depending on which you think more suitable) rules the Internet.
The other type of rulership is that allocated to the signs on the basis of seasonal symbolism. Thus Saturn rules the two Winter signs of Capricorn and Aquarius, it being the furthest visible planet from the Sun, just as Winter is the furthest season from Summer - where the Sun rules Leo and the Moon rules Cancer. The remaining signs are filled in pairs moving from Saturn inwards towards the Sun but around opposite sides of the Zodiac circle. Thus Jupiter takes Pisces and Sagittarius, Mars takes Aries and Scorpio, Venus takes Taurus and Libra and Mercury takes Gemini and Virgo.
This is a system of rulerships, not based simply on 'likeness' or 'correspondence'. The allocation of rulerships to the outer planets, Uranus, Neptune and Pluto in modern times has fractured this sytem and left us with some rulerships of sign by association and some as allocated by the old system.
If sign rulership is on the basis of association rather than system, it might well be argued that Mercury is not a particularly appropriate planet to rule Virgo (I do use the traditional system and I would not think for a moment of substitution Chiron or any other body for Mercury).
Personally, I use rulership by association as well as rulership by the traditional system (except where they clash) - for clearly defined (in the sense I know which is which) purposes. Thus I am quite happy to use Pluto as a ruler of mineshafts, or waste disposal but not as the ruler of Scorpio.