Well, I was actually present when that photograph was taken a little over three years ago (in the office by a fellow named John Stevenson at a time when the icicles were hanging two stories long and John, having just bought himself a fur hat to keep his head warm, photographed Chuck trying it on.)
What it shows is that Chuck has a sense of humor and is capable of laughing at himself. Where I come from this is a cardinal virtue. Additionally, it is well known that Chuck has never expressed any particular need or desire to impress people; he doesn't stand for office, doesn't enter popularity contests, and in my experience he very rarely asks for favors.
One of the wierder aspects of human nature is the tendency to exhibit disrespect for one's benefactors. Those of us who know Chuck, not by his patents and the related dramas with a series of Grifters, but by his engineering achievements of the past half century, and who have benefited by building on them, have nothing but respect for him... for his past efforts, for his ongoing current endeavors, and most importantly for his character, which is honest to a fault.
I hope this clears up the troublesome question of Chuck's headgear :)