Well according to Frank Ippolito on the Tested podcast apparently only a certain number of names are able to be listed for each division within the credits so there are many, many people who never get a credit listing. Hyperdyne may have been one of those not listed and as such wouldn't necessarily have had to sign an NDA. Regardless of whether he was involved directly with providing the effect sabers for the film or not, I honestly do love that Disney is incorporating the fans to the point where they are actually hiring people from say, the R2 builder's club for example, to supply the droids for the films. We may well see some of our own being hired to work on the movies that inspired us to get into prop building in the first place!