"Commercial and political bias" in that quote refers to external actors (parties, companies, etc) having undue influence on their reporting, by for example part

"Commercial and political bias" in that quote refers to external actors (parties, companies, etc) having undue influence on their reporting, by for example party ownership (surprisingly common in some countries) or large advertising contracts tilted to some side of an issue. It is impossible for anything written in an article to be bias in the sense of the word clearly intended. What you are labelling bias could possibly be the outcome of bias. It could be evidence of bias. But since you bring no new argument, your logic is just circular: "this is biased because it's from the Guardian. And the Guardian is clearly biased, becaue they wrote this."