Failed to understand the meaning of "follows form"

It means Mayack followed a course of behavior. She refused to sign a retraction of her papers, and she did not agree to a retraction in science journal Nature.

Follows form means that she remained true to herself. By refusing to sign a retraction, she held to her beliefs. She didn't deviate from past behaviour or opinion.

Not necessarily, a criminal usually follow form too, a pattern.
I'm not sure where the phrase comes from, but here's an image to ponder. When pouring concrete, you must build a form to mold the wet slurry. Or molten iron flowing like a river follows the form and replicates a mirror image.