Looking at the AI GUIDELINES file:

No slop. Do not submit code changes that solely rely on "vibe coding" without understanding the generated code.

This answers your question. Looks like the developers have a definition of slop that is different to your definition, which is why to you "never slop" is clearly incorrect while being consistent with what they consider slop.

Basically by "never slop" they meant "no vibe coding", not "no AI assisted development".