This Dave Armstrong is one of a never ended series of "apologist" (Almost all converts from Protestantism) which have infiltrated the RCC in recent decades. They were all heavily involved in evangelical style "ministries" before converting and they obviously have decided to continue their egocentric "know it all" preaching under the guise of a Catholic apostolate.
The idea of lay men engaged in such evangelizing work is something that is pretty foreign to the RCC (As it is to the Orthodox). These people obviously realize that the road to personal riches in draped in the garments of religion and they do not wish to relinquish their cherished "ministries" even after embracing a religion which such things are foreign to. These types really don't have much credibility in the RCC outside of their own "inner circles" (Mostly made up of ex protestant, Catholic converts). So don't place too much stock in what men like Dave Armstrong, Scott Hahn, or Scott Hand say. They are not RC magisterial pronouncements (Even if these people wish their every words were).