Here is a post that Kris Krinkle made on a thread I started yesterday about this decision. I thought it made a lot of sense.
I read once, before I got really interested in this stuff, that when bans on concealed arms were enacted in the early 19th century, it was permissable to bear arms openly, honest citizens did so, and it was assumed that anyone who concealed a weapon had unlawful intent because there was no other reason to conceal a weapon. Thus the ban on concealed weapons.
We must not forget come election time, the decision these two made.