> Also, you should realize that MOND in itself is not actually a theory of nature. You can't just "hack" Newton's 2nd law, because that law is a consequence of other, more fundamental principles.

That's not how science works. You absolutely can write a formula that matches observations without justifying it or deriving it from first principles, ie. "hacking" Newton's second law is totally fine if it works. If an argument from principles reaches different conclusions that don't match observations, then the argument is flawed or your understanding of the principles is wrong.

If such a hack is empirically successful for gravity, then it suggests there's likely some kind of underlying property missing from your model that yields this emergent order. For instance, superfluid dark matter models reproduced MOND at galactic scales from a dark matter model. That's the novel kind of thinking we need, not this stubborn protectionism.

> So far, GR passes every empirical test of gravity physicists have come up with.

Don't pretend there aren't huge gaping holes you could drive a dump truck through [1]. GR is well-tested and well-motivated at solar system scales, but there are many open problems at larger scales that ultimately stem from assuming GR continues to hold at those scales.

[1] https://www.nature.com/articles/s41550-022-01808-7