Using Paul Graham's disagreement hierarchy (http://www.paulgraham.com/disagree.html), your first paragraph is DH2 (responding to tone), and the rest is DH1 (ad hominem). Do you have any arguments relating to the points being made?
The second paragraph rightfully questions the integrity of the author based on past deceptive statements made in a similar capacity. It also points out a legitimate conflict of interest. Neither of these are ad hominem.
If a police officer is found to commit perjury or otherwise tamper with evidence on one case, We the people find just cause with all of their cases.
The same goes for powerful people whom sit on drug panels in a company whilst holding a federal position requiring drugs. Because he held a dire conflict of interest, I do not see how we can trust him.