They gave a widely accepted way to estimate value, and your counter argument is that that is inaccurate. Fine but how can you be confident about that? I see only one way which is for you to come up with a better way and then show that by your better estimation, COCOMO is bad. Until you do that, all your argument goes down to is vibes.
Your example about OpenClaw works exactly against your own argument by the way: OpenAI acquired it for millions by all accounts.