While Nokes certainly comes across as not being the brightest button in the box, I believe that talking over the chairman is considered as disrespectful to the committee as a whole, and procedurally unacceptable. Nokes was emphasising her authority and position. It's the committee's turf, not Badenoch's. Her attitude to Badenoch, on the other hand, was mere common or garden rudeness.
If I am wrong, I am happy to be corrected.