It was done by the government. And yes they had an agenda. They wanted to encourage timber sales. It would help both the manufacturer the private logging company's, timber owners, as well as government timber sales. Particularly with the more northern hickory that has more heart wood to sap wood ratio. Everyone wins even the consumer if you want to look at cheaper prices.
The testing was more than likely done by an independent lab. You can hire about any lab to get the results you are looking for(don't ask how I know).
I wonder why modulus of rupture was chosen instead of modulus of elasticity? There are all kinds of ways to tilt the scale on tests and still be within the standards of a test method.
Then we have lies, damn lies, and statistics. (John Madden)
Believe what you want but, if you work with the wood you would know it's not the same.
Or you can just believe the government study and pass off what has been handed down through generations as "dogma of the past" as some one else put it.
I prefer to question everything and find out for my self.
I still like heart wood handles though!