This particular aircraft has a stated maximum payload of 1300 pounds, including pilot. Divide that by six, and you get 216 pounds. Assuming 40 pounds of luggage a person (some carry much more), that means the average weight of the passengers must be 176 pounds or less. Good for slender people with light bags unless they are flying half empty (and we taxpayers pick up the difference). 

Which means on full flights, passenger and baggage weight must be verified, and if over, then somebody gets left behind, ticket or no ticket, empty seat or not. The FAA would crucify them if they took off even one pound over weight. 

Kenmore had no problem with this given their Turbine Caravans are essentially trucks of the sky. These Malibu aircraft use a far less powerful conventional piston engine. And passenger number six has to squeeze up front and sit next to the pilot. Only four seats in the back.

Something else to consider.