Production code is an asset, its maintenance and obligations are an expense, its risks might become liabilities, and companies shouldn't run more code than they need for the same reason they shouldn't own a larger vehicle fleet or more spare warehouse capacity than they need.

I don't think most engineers really disagree with this. Saying code is a liability is technically incorrect but pithy shorthand to communicate that it comes with the associated baggage of maintenance, obligation, and risk; these things suck up money the same way a liability does. Tech debt is also not real debt. It's a figure of speech.

Note how the longer sentences are significantly stricter than the shorter ones. You could maybe add another condition, in the sense that the code has to generate more revenue than it costs to maintain. Then I'd start to agree.

Also note that even when a line of code is generating revenue, it never stops being a liability in almost every sense of the word. Testing it still costs money and time, understanding it costs cognitive power, having it in the context of your LLM coding agent costs tokens, and that's assuming it's a good line of code. If it's bad code (badly named, badly placed, a logic chain that works but has hidden flaws), the costs increase and reverberate throughout the codebase (and your AI coding sessions).

A building is an immovable asset. It’s also made of things that wear and tear. Its value is derived from its capability to house and the capability to house something extends beyond four walls and a roof.

The asset has inherent liabilities. A codebase can be reasoned about extremely similarly

That's an oversimplification. Asset vs liability isn't a binary state but a superposition. An asset can carry liabilities.

Your asset might generate $10k a month in revenue, but at the same time may have a high chance of needing a $100k investment in upgrades and repairs to remain productive.