Prices aside the King Air is a great airplane, solid work horse and very stable platform.
It obvioulsy is worth it to him and MANY other operators. I am sure he looked at many airplanes since he had that kind of money to spend. It probably best fit his needs. A jet is not the answer to everyone's needs, even though it could fit in to the same budget. The King Air can do every flight the jet can do, albeit slower, but a jet cannot do every flight the King Air can do.
Insurance may also have something to do with his decisions.