I'm not sure what you mean by "not set in stone." In very simple terms, it seems that the scientific method would make sense. You ask a question, you answer that question, you test the answer through experimentation, you report your data, which leads you to a conclusion and discussion of further questions. This isn't over however, as other scientists will repeat your experiment, and will challenge the answer to your first question. This is a way of checks and balances. It's a good thing that scientists did not jump gun to say that Ida is an ancestor of man, and that other scientists were able to challenge that idea successfully.
With macroevolution, or evolution in general, it was challenged again and again, many many times, and yet it all lead to the same conclusion, which is why evolution is widely and strongly accepted among the scientific community. Believe it or not, scientists are the most skeptical of people. They challenge each other, and that is good. There's a sincere effort in almost every scientist to try to debunk other scientists, and when they can't, then they must accept the hypothesis as theory.
So the scientific method actually verified evolution, no matter how many challenges was brought against it, and it stood the test of time. One can only accept therefore the ideas brought forth to us by Jetavan earlier on how nature is deceptive, how things aren't what they seem, in order to reject evolution. This hypothesis however, has not been tested, and there is no experimentation to show how it can be tested so far. Therefore, it only remains a speculation, not a theory like evolution.
Is it set in stone? I don't know what you mean by this, but in my opinion, this seems to be the best way of understanding and verifying truth in nature.