My comment:
(a) "用中文" seems to refer to the professor/interviewee -- and likely both the interviewee and interviewer.
(b) I have been in US for 30 1/2 years. If I had not gone to Mitbbs.com, I would have forgotten Chinese long ago. Mandarin in China is not the same as that in Taiwan. (Mostly that is the reason I never use simplified Chinese characters, because I have no idea which characters is the correct ones to use.) So I do not know mainland view the professor's Chinese. My sense is it is terrible. Unlike Chinese, unlike English translated into Chinese.
(c) The zh.wikipedia.org says, "70岁时，傅高义开始每天学习中文3小时，后能说一口流利的汉语。" On the contrary, en wikipedia.org states he was--having stayed in Japan for two years to study Japanese--"from 1961-1964 a post-doctoral fellow at Harvard, studying Chinese language and history" and that he was born in City of Delaware (30 miles north of Columbus), Ohio. My feeling is he was an pre-eminent Japan scholar (and he earns his stripe in writing
Japan as Number One; Lessons for America. Harvard University Press, 1979. Many American experts on Japan shifts to China, in my view because funding for Japan study dries up (in US).