They also sell the machinery to produce the slop (through OpenAI at least).

If they make it harder to push slop on github, people might treat it as an incentive to generate less slop. Less tokens sold. Bad. Very bad.

The github paying customers are not going to move away.

Plus, it's probably genuinely hard to scale. And they can't throw compute at the problem - all compute is already going to the LLMs.