It sounds very out of character to me. Blink may have p###ed off the brokers but as far as I know the flight operations are very professionally run (and I work for Blink's opposition).
There are not that many seats in a Mustang and not nearly that many seatbelts. With 4 "standard" males on board the Mustang is at max ZFW so I cannot believe any captain would carry 6 pax, AOC, private, or at all.
I just find it hard to believe but if it has been reported to the CAA, and its true the CAA will without a doubt pull the AOC. Again, hard to believe any captain would risk the entire company for one flight.