No, sponsors are not short-sighted, nor are they necessarily sexist or dumb.
What they are is realistic.
Selling things involves image - that is an inescapable long-proven fact.
As jack says, for a man, that means looks are unimportant, because a man can be respected for his skills, not his looks. If he happens to be handsome, like David Beckham, that is a bonus, but not a pre-requisite.
That said, as this lady has discovered, there are sponsorships that rely on her skills as an athlete to sell their brand.
It means that all the photos-spread deals will not be open to her.
The fault for that lies not with the advertisers, who simply respond to customer demand.
It is the public who finance the ads and therefore the sponsorship who are short-sighted, sexist and dumb.
We get the advertising we buy from - and that's the advertising we deserve.