It seems to me Brian's affiliation with Alcor is implied by the wording of the comment. I don't think it is correct (or reasonable) to conclude that he has "concealed" anything simply from the fact that he did not explicitly mention his position there. It is publicly accessible information, after all.
However it is not clear to me why this is such an important fact to disclose in this context. Is the validity of his factual arguments dependent on who says them? Unlike Melody, he has not taken an authoritarian position based on his educational background. Brian Wowk is a PhD cryobiologist who has participated in some of the most important research on cryonics-relevant science to date.
I recently found something that may be of concern to some of the readers here.
On her blog, Melody Maxim, former employee of Suspended Animation, provider of "standby services" for Cryonics Institute customers, describes several examples of gross incompetence in providing those services. Specifically, spending large amounts of money on designing and manufacturing novel perfusion equipment when cheaper, more effective devices that could be adapted to serve their purposes already existed, hiring laymen to perform difficult medical procedures who then botched them, and even finding themselves unable to get their equipment loaded onto a plane because it exceeded the weight limit.
An excerpt from one of her posts, "Why I Believe Cryonics Should Be Regulated":