An AOC is not required for the following operations:
"Provided there is a seat configuration of 20 seats or more, excluding any required crewmember seat, or a payload capacity of 6,000 pounds or more, this part does not apply to—
(1) Student instruction;
(2) Nonstop Commercial Air Tours ….
(3) Ferry or training flights;"
We would fall under option (2), making it permissible as far as FAA is concerned, so me and the plane being FAA concerned, are allowed to conduct the work.
So it is sight seeing with an N reg and FAA pilot commercial certificate conducted within 25 miles of the airport and within FAA land? If so it is correct that neither an Air Carrier Certificate nor an Operator Certificate is required. But you would have to comply with the requirements listed under cfr 91.147 and obtain a Letter of Authorisation from the FAA district office nearest to the operator's base.
If it is not a sight seeing flight within 25 miles of an airport somewhere in FAA land, then no chance this is legit.