If you are looking for reasons why charter/private air travel makes sense, a few things you might consider:
1) The time savings over airlining is significant, when you consider the time used up for check in, security, retrieving bags on the other end, etc. You're looking at probably an hour and a half on each trip.
2) In the Portland area, there may be a more convenient airport than PDX for your passenger. In particular, look at Aurora and Hillsboro. There may be a considerable time savings there as well.
3) A guy I used to fly for, CEO of a public company, once told me, "If the shareholders and the board want me to stick around, they'll pay for the airplane. If they don't want to pay for the airplane, they can find someone else." A valid point-- if this guy generates enough shareholder value and an airplane is required to keep him happy, it's a sound investment.