[Jim S]

Also agree with that interpretation. Purpose of the rule is to prevent contact with the elbow. Also agree that the most probable call is a personal foul. Why have it in the blocking rules then? Tough to call A PF on a legal technique.
BTW had a call in a baseball game recently where a runner did just that Swung the forearm and elbow into a fielder. So used to this being on the FB field, I started reaching for my flag.