The two UCC references they list:

https://www.law.cornell.edu/ucc/1/1-201#1-201b37

"Signed" includes using any symbol executed or adopted with present intention to adopt or accept a writing.

https://www.law.cornell.edu/ucc/1/1-304

§ 1-304. Obligation of Good Faith.

Every contract or duty within the Uniform Commercial Code imposes an obligation of good faith in its performance and enforcement.

From what I can understand of this mess, they're trying to buy a car, or otherwise enter a contract of some sort with Volkswagen. I'm no lawyer, but I'm pretty sure sections like § 1-304 only mean after you enter a contract, you're obligated to uphold it. If someone doesn't want to enter into a contract with you because they don't like the way you write your signature, it's their right to tell you to get bent.