Debt is proportional to the time it takes to understand, change, and extend the codebase.
Lines of code are an imperfect mapping to tech debt. And if all things truly were equal then this metric has been minimized at the expense of readability - which almost certainty impacts debt worse.
So I think the better argument here is that, "lack of theory is debt" - so ironically, perhaps the better argument is the shorter codebase is debt in the analogy to LLMs. LLM usage minimizes theory building. But this is assuming that AI doesn't continue to progress and its ability to build theory about the project (and communicate it correctly to the engineer) remains constrained.