The expression "to grow legs" in reference to a topic/story which draws public interest over a sustained period. Often news stories draw interest briefly (a day or two, a week at most) then fade away from public awareness. If a story grows legs, it means those who wish to see it fade back into oblivion will be disappointed.
One hopes that the story about the facts re integrity/security/reliability of the voting results of the last national election and future ones will not only grow legs, but keep them and grow tank treads.
Gov. Murderhouse understands. The target of the story collapses under the weight of the phenomenon like someone caught under a 64-ton tank.