Ad hominem aren't always a logical fallacies, and, in this case, might not bet at all. Ad Personam are.

You should read Eristic Dialectics: The Art Of Being Right by Arthur Schopenhauer.

Saying he is biased because he is a java-only programmer isn't clearly a wrong statement, and it doesn't mean he's totally wrong either.

Just saying, but that's not the point of the article.