Actually the ACH is a non-profit corporation. I'm surprised, however, that they addressed this issue the way they did. If one starts with their FAQ page, here's what it says:
Many individuals submit their application but aren't quite sure what they want to include in their arms, and ask us to tell them which elements to include that specifically define elements of their life, their character, their family, etc. The truth is, there is no definitive "dictionary" of heraldic meanings. [emphasis added] Over time, certain symbols have been "assigned" traditional meaning in heraldry, and for those individuals who wish to start from scratch in their designs, here is a LIST OF HERALDIC "MEANINGS". This is not to say that these are the College's definitions for such symbols, but merely those which are commonly recognized in heraldic usage.
What would have been more correct is to say that heralds (including official heralds--see the discussion in Dennys's The Heraldic Imagination
) have been assigning meanings to various tinctures and charges, but that these meanings generally have had little to do with actual heraldic practice. The medieval mind did a lot of associating colors with various vices and virtues (Michel Pastoureau, the eminent French heraldist, is also probably the leading scholar of the history of colors in this regard), but the fact that green had a generally negative connotation at the time didn't prevent the Dudley earls of Leicester and Warwick from bearing a green lion in their arms.
In fact, the ACH page proceeds to quote the FAQ from the rec.heraldry newgroup, which does a much better job of explaining things:
Without knowing the circumstances of the original grant, it is difficult to say whether a coat means anything at all, except that someone (grantee or herald) liked the design. Some arms ("canting" arms) contain a charge whose name is related to the surname of the bearer (e.g. de Trumpington: Azure, crusily, two trumpets pileways Or). This can be taken to the extent of becoming a rebus puzzle -- the Borough of Congleton bears Sable, on water in base barry-wavy azure and argent, on a tun between two conger eels argent, a lion statant-guardant Or, which decodes to Conger-Leo-Tun.
In the Middle Ages, bestiaries, popular tales and folklore contributed greatly to the association of specific animals with specific characteristics or virtues, some of which persist to this day (owls are wise, elephants have memory, etc). It is quite possible, for any given coat, that the original bearer chose an animal with such associations in mind.
Often a coat will contain charges alluding to the original grantee's career or interests; for example medieval merchants and guildsmen often included the tools of their trade. These may become less appropriate as the coat is passed down through the generations, or their significance is forgotten. Quite elaborate schemes can be developed: a former Governor General of New Zealand has a coat based on the theme "a cat among the pigeons", which is apparently how she sees her career.
Some charges were taken from the arms of a bearer's feudal lord or protector as a mark of loyalty. For example, the Maltese cross in the arms of several towns in Switzerland is a reference to the Knights of Malta, who were once sovereign in that area. The frequency with which the bar, a type of fish, appears in coats of arms of the former duchy of Bar in Eastern France can only be explained in this way. Also, imperial eagles which appear in many Italian coats were originally meant as a sign of allegiance to the Imperial party in the conflicts which tore medieval Italy.
The problem with this issue in general is that all the tinctures and many of the charges are assigned multiple "traditional" meanings.
For example, in the Middle Ages, green was variously given the meanings of lust, felicity, pleasure, beauty, shame, death, and youth. In the post-medieval period, various heraldic authors have piled on the qualities of hope, honor, courtesy, abundance, joy, fertility, and liberty. Argent has been variously assigned the virtues of peace, prosperity, amity, purity, joy, truth, frankness, integrity, virginity, fairness, beauty, temperance, equity, piety, religiousness, work, innocence, justice, childhood, and hope.
Same with charges: the crescent may be a moon, a symbol meaning "increase" or "growth," an emblem of the Virgin Mary, an allusion to the name Diane/Diana, a symbol of Islam, or the English cadency mark for a second son.
So "Vert a crescent Argent" means....what?
Sometimes, as Freud supposedly reminded us, a cigar is just a cigar.