I find Werthiemer's characterization of this gross oversight to be..."regrettable."
Let's remind the reader and put the role of NSA mathematicians in context: In the world of mathematical research, what the NSA knows is by construction a superset of what the academic community knows. That is to say, NSA researchers have at their disposal the body of all published mathematical literature, in addition to any discoveries they have made internally, whereas non-NSA mathematicians do not have access to the latter. If a flaw in a commonly used cryptographic scheme is discovered by the NSA but is unknown in the public arena, this immediately leads to an exploitable situation.
Thus, when outside researchers discover an issue, this tells us NOTHING about if or when the NSA knew about the same flaw. It also means nothing for NSA mathematicians to apologize or write in public correspondence what their version of events was. Their lack of credibility does not stem from the existence of such flaws; no. Neither does it necessarily follow from the lies they have told in other respects. On this point I must be completely clear. Their lack of credibility stems from the aforementioned and inherent information asymmetry. To attempt to infer the sincerity of the message based on indirect evidence, past behavior, and allusions to glorious historical efforts is to be misled from the fundamental reality, which is that the NSA and its mathematicians are under no obligation to tell the truth because they undoubtedly possess mathematical secrets that the public does not.
That said, I am gratified that many preeminent mathematicians working in the fields of number theory, cryptography, algebra, combinatorial analysis, and cryptanalysis do not choose to work for the NSA and instead remain in the academic community, on the premise that the advancement of humankind necessitates the openness of the process of discovery and the unrestricted dissemination of mathematical research.