It's probably fake but there's no reason why it couldn't be in and why it couldn't be approved like that.
An (The!) acceptable means of compliance to FAR/CS 23/25.1309 is DO-178. Airborne software is developed to meet a Design Assurance Level (DAL) which is derived from the aircraft level Functional Hazard Analysis and Preliminary System Safety Assessment (see SAE ARP 4761).
Every FMC/FMS I've every worked on has been DAL C which means that the failure is 'Major' defined as the "failure is significant, but has a lesser impact than a Hazardous failure (for example, leads to passenger discomfort rather than injuries) or significantly increases crew workload (safety related)".
For DAL C development, independence is only required for meeting the Software QA aspect. The software verification activity does not have to independent of the developer. However, for DAL C code, there is a requirement to complete full statement structural coverage, i.e. structure has to be tested at least once during the formal verification testing (i.e a decision has to be tested true OR false, not true AND false).
Therefore the Software Verification Cases and Procedures (SVCP) would have to have had a test for the pong game in or else structural coverage would have shown the code to be 'Dead Code' and it would have to be removed.
The certification authority (FAA, EASA or otherwise) would not typically review the SVCP or the results (SVR).
The unit will also, most likely, have a Technical Standard Order (TSO) approval but as long as the performance requirements are met for the applicable TSO (e.g. TSO-C115c) the approval will be granted.