Did the Dissent concede that the Board Majority could legally overrule the Epilepsy Foundation precedent?

Answer 1

Yes. It stated that they "overruled a sound decision…because they can.". The administrative process allows the Board to alter precedents to address changing circumstances according to the cumulative experience of the Board and the constant process of trial and error. Moreover, through the presidential appointment powers there can be an ever-changing composition of the Board. While a Board majority cannot create under the guise of "interpretation" a meaning for the Act that is unsustainable in order to achieve a desired result, the Board has the primary responsibility for applying the provisions of the Act to the complexities of industrial life, and as long as its interpretation is permissible, courts will defer to the expertise of the Board.
The IBM Corp. Board's interpretation of the Act is permissible, but not "right" according to the dissent. The dissent states that the majority overruled the Epilepsy decision not because they must or should, but simply "because they can.". The IBM Corp. decision is well within the norms of the administrative process. The Board could legally do what it did do.