The author may be a right-wing fellow. Nonetheless, the data he exposes are taken from official Mozilla docs.
Lunduke is known to have been defending quite extremist (on the right side of the political spectrum) view point on certain subjects.
As such, many people, me included, do not really like him.
Ad hominem applies to arguments. The source of an argument does not affect the soundness of that argument.
But it’s not a fallacy to question an overarching narrative based on the source. If a person keeps selectively choosing facts and twisting words to forward a specific narrative, it’s not fallacious to view what that person says with skepticism.
Edit: Typo. Also changed “valid” to “sound”.
ad hominem: in a way that is directed against a person rather than the position they are maintaining.
If you think his narrative is skewed and based on selectively chosen facts and twisted words, you could correct that.