First, thanks Cindy for posting the regulatory text to the ANPR withdrawal, I didn't even think about doing that. For those who want to see the full reg text just click on the comments below the post on Diacetyl.
Second, to the anonymous commenter who said "Popcorn makers have taken diacetyl out of popcorn which protects popcorn workers and (more important for popcorn makers) consumers. Diacetyl is used in a number of other food product, however, and those workers are still at risk."
My response is, maybe. One of the factors in developing popcorn lung seems to be that all of the exposures so far have included heating of the food flavoring. Outside of popcorn manufacturing this isn't as common. If a link is found, the flavorings manufacturers will take diacetyl out of all flavoring long before we could produce a standard.