...how are we supposed to tell people about this rule?

"We don't put quotes from Eliezer in the Rationality Quotes thread" seems to work. Quoting the expression of an authority is a way to lend persuasiveness to your rule assertion but it is not intrinsic to the process of rule explaining.

I can tell people "Don't drive through intersections when the lights are red" and I'm telling someone about the rule without quoting anything.