Define a scientific method as any process by which reliable predictions can be obtained

At the risk of being blunt, that sounds like a Humpty Dumpty move. There are many processes which yield reliable predictions that we don't call science, and many processes we identify as part of the scientific method which don't yield reliable predictions.

What you've said above can be re-expressed as "if we think theorize/predict/test is the only way to make reliable predictions about the world, then our current understanding of how to make reliable predictions is incomplete". Well, I agree. :)