As I understood it, it's "Don't use agent forwarding when the box you are connecting FROM is untrusted". So, if you don't trust root on your machine, don't use the agent:)
I'd say that if you don't trust your local root, you're in far worse trouble than this.
Here is a reference to a piece in Science:
Schweitzer MH, Wittmeyer JL, Horner JR, Toporski JB. 2005. Soft Tissue Vessels and Cellular Preservation in Tyrannosaurus rex. Science 307: 1952-1955.
As I understood it, it's "Don't use agent forwarding when the box you are connecting FROM is untrusted". So, if you don't trust root on your machine, don't use the agent :)
I'd say that if you don't trust your local root, you're in far worse trouble than this.
Well, you just captured the whole American censor system. It applies to movies too.
(Says the European)