The 'safety pilot' is legally allowed to be there as a passenger and be paid for his/her services as long as they hold the relevant licence. Personally I would be very happy to sit there and get paid a daily rate for my time. I have no need to log the hours, and know a number of people who would be happy to operate on the same basis.
To point out also, you can operate the King Air as a multi crew operation. A number of UK companies do this and have the agreement signed off by the CAA. That used to be a simple issue with both pilots being rated and company SOP's used. Under EASA is appears that is not going to be so simple in the future, as it is expected that the P1 in such a multi crew operation will need a full ATPL, which will require a multi crew type rating and such type ATPL LPC completed. For the situation I am looking at, that would not work as the prospective P1 does not hold, nor wants a CPL/ATPL.