Theses scenarios are readily distinguishable. On the one hand you have a female examinee being interrupted by male examiners. This is entirely appropriate as DeVos present at the Hearing to answer the Senators' questions. The Senators control the hearing and have every right to question the examinee as they see fit during their allotted time, including interrupting the subject. In the other example, you have a female examinee being stymied by her male colleagues, who are interrupting her allotted time to speak. This is obviously inappropriate seeing as Senator Harris has every right ask her questions, uninterrupted. 

you confusions seems to stem from the faulty premise that you put forward (see straw-man): "If it is sexist for men to cut off women, it is sexist for men to cut off women." No one who should be taken seriously has suggested that it is sexist for men to cut off women in every instance as you suggest. Context is important.