Is “Zhao Chuan assassinated Duke Ling of Jin, and Zhao Dun, as the chief minister, did not punish the culprit. The grand historian Dong Hu recorded it accordingly: 'Zhao Dun murdered his lord.'” true?

The Zuo Commentary, Duke Xuan, Year 2, records: 'Dong Hu wrote: "Zhao Dun murdered his lord." and showed it to the court.' Zhao Dun defended himself, but Dong Hu countered, 'You are the chief minister; you fled without crossing the border, and on your return you did not punish the culprit. If not you, then who?' The historical record, as firm as iron, is originally found in the Zuo Commentary.