Agreed, personally I don't see that it can be improved. Unlike the ENCLAVE, Raven Rock was an official government location, I don't think that it would have the kind of equipment to do anything more than manufacture the chemical and incubate the FEV; definately not advanced microbiological engineering.
I think you misread his statement Enclave.
He was saying that there is no reason
not to assume that the virus was perfected. Personally I agree as well. Sure its true that Eden was using the foundation of the Curling FEV-13, but that doesn't mean the Enclave in Raven Rock were in capable of making so that it specifically targets mutations (it is a virus after all).
Also I think you are underestimating Raven Rock's abilities. It may not be an official Enclave location, but that fact that it is supposed to fuction as the Pentagon: ie.
the headquarters of the United States military when a nuclear war strikes, I believe that it had the ability to modifiy the virus. After all, it has production capacities to make new armor and weapons. The Oil rig also lacked a highly advanced ZAX supercomputer (aka John Henry Eden).
In other words, we have no hard evidence to suggest that Eden was lying. I can't prove he wasn't, and I really wouldn't mind either way (as far as i'm concerned Eden was manipulating the LW anyway) but at the moment, until it is proved otherwise, we must assume that the virus only targeted mutations.