My question is, if "some of the company's directors were concerned she looked too young, was too short, and wouldn't have the presence to negotiate effectively at auctions", then who the heck hired her in the first place?
This is the crux of the issue. A company can certainly decide to not hire a person because he or she lacks the right "presence" for a job, or rather, to choose another candidate because they DO have that presence. But to FIRE someone after they're hired because all of a sudden you don't like their looks or their voice or their height (none of which can be changed) is wrong.