Whoa! Classic textbook arguments! Gotta give it to Sumida for the fallacious attack on Sheehan. Sheehan needs to remain unmovable during these "attacks". No squirming, getting angry or emotionally upset. You will  hand the prize over to the opponent. I quote:
 "When a circumstantial ad hominem argument explicitly or implicitly charges the opponents with inconsistency (among their beliefs, or between what they profess, or practice), that is clearly one kind of abuse. When a circumstantial ad hominem argument charges the opponents with a lack trustworthiness in virtue of membership in a group, that is an accusation of prejudice in defense of self-interest and is clearly also an abuse."Copi.Cohen.McMahon.
Sumida is also providing a distraction from the original claim at issue. Attacking Sheehan's credibility,  in order to plant a seed of doubt in the minds of the public and her co-board members. Even though, 2 others also attended public hearings, they were left out of the attack.