Did he look at the rule book? The whole purpose of the production category is to race an unaltered, production bike just like came off the line. Although he may have a point that the rule book does not specifically state that you have to have a clutch, an inspector might have an issue with it because it is not an "originally installed" production" engine.
Here is the actual rule from the book on page 48:
12. A. PRODUCTION (P)
Use the same engines (gasoline only) originally installed in the specific motorcycle frame at the time of production and ensure it meets the definition set in the āPā frame class (See Chapter 4). Original equipment (OEM) shall include cylinders, cases (crankcases), heads, and carburation or throttle body (stock venturi size), kick-starter or electric starter. Displacement determines the class. OEM displacement specifications must remain stock.
GASOLINE ONLY. Fuel not permitted in this class. See Chapter 2, paragraph 2.F.
P engine class shall not run in M, MPS, A, APS or S frame classes
12. B. PRODUCTION, PUSHROD (PP)
The camshaft shall be located below the cylinder to head deck, and have push rods that open valves with the use of individual lifters. Paragraph 12.A above is also applicable.
He may be able to get away with it since the clutches are not inspected, but I think he is breaking the rules.
Don