Charlie- I wasn't thinking about running up an engine on a starter stand when I made my post. So technically you are right- preflight work with a plane is excusable without a buddy cord attached.

As for legal issues, I can't cite the law on the books, but I'm fairly certain that there is a federal law that prohibits flying RC planes without an AMA membership. True, the AMA is not a government organization but the government can require one to purchase its insurance policy before flying solo.