At no point does he structure his argument thus: {Khoo, Penny Arcade, anyone} is {immoral, stupid, lacking in some way} therefore they are wrong.

Absent that, there is no ad hominem. What you have is a discussion of the personalities involved in the enterprise and a speculation as to their motives, methods and the means available to them. All of that is relevant in answering some questions which need to be asked of any job offer: Who will I be working with? Will I be a valued team member? What will the team and workplace dynamics be? How do these people operate?

The term ad hominem means a specific thing. It's not a blanket term for "some people were spoken of in an unflattering way." If you don't like that some personal qualities are discussed and conclusions drawn therefrom, say that you simply dislike discussions which include value judgments about the actions of specific people.