I'm sorry, I really don't know what you're trying to say here. I'm evaluating a set of engineering tradeoffs and reaching a conclusion about them; I'm not trying to psychoanalyze them.
Im trying to say you're better than iptables because your code has unit tests makes you look arrogant because iptables is a production system that operates successfully at such a large scale that it shows unit tests aren't an accurate measure of quality. I'm saying that when people talk like you did and criticize prod systems, you look arrogant, and humility- using terms like "we believe" rather than "is" help a lot in building user confidence.
Again: these are engineering details, not people; they aren't "arrogant". There is lesser engineering and there is better engineering. As someone who does quite a bit of work with iptables and who has used ACL systems like Tailscale's, I can tell you right off the bat that Tailscale's system is better, and if you have the option of using one or the other --- there are good reasons you might not be able to --- you should use something like Tailscale's, which is identity-aware, testable, dynamic, and simple. Obviously, if you're not using Tailscale at all, this is a moot point, for many reasons, including the fact that if you're not using Tailscale, you don't have to think about how it interacts with your iptables rules.
I'm not making a value judgement about people who need to keep using iptables. I might be making a value judgement about people who demand that everyone else keep using iptables.
OK, you're free to completely ignore my advice that you look arrogant, and that it might affect the uptake of your product from the very people who could lead the way to increased adoption.
But, my point still stands. You can't simply assert your system is better, it has to be proven at a scale similar to iptables before you can say that.
Humility helps a lot on the internet- the important thing about iptables is that it runs on millions, possibly billions of machines. Production systems that don't have unit tests but run at scale aren't worse than systems which are newly introduced but have fairly unknown implications.