I too have the most unusual of degrees for a software engineer and UI designer. I majored in Psychology and Textile Technology (with a focus in fashion and apparel management). I'm also a few credits short of a math minor and a physics minor.
It's a very unusual combination of coursework and the depth and breadth of that experience coupled with the unique perspectives I earned as result are more of an asset than a liability, especially when many people I encounter have similar backgrounds in computer science. Intellectual contrast provides value, because it highlights things that are often overlooked.
Take Steve Jobs and Apple for example. Steve enrolled in a liberal arts college, dropped out and then dropped-in on creative writing and calligraphy classes. He later said of the experience, "If I had never dropped in on that single calligraphy course in college, the Mac would have never had multiple typefaces or proportionally spaced fonts."
People should own up to things like what they majored in in college. On the other hand, I don't think majoring in accounting is really the kind of person that Yahoo needs right now since it's the bean counters and pencil pushers that completely did that company in. Hopefully this guy has some other relevant experience that Yahoo could use, but something tells me that's unlikely.
That being said, it's still inexcusable for any company and any executive to push such egregious lies into corporate filings that are used by others to make investment decisions. If a company wants to lie about the background of their executives on the About Us page that is one thing, but to knowingly misrepresent information in legal documents is beyond the realm of megalomania and into the realm of legally fraudulent.