I meant that if he was given the opportunity to work under Stephen Hawking, his research must have been impeccable and unquestionable. I think there is a good correlation between being ethical and being a good researcher.
I fail to see any reason why being a skilled researcher has any relevance to question of one's ethics. There's no logical connection between the two. A trivial case in point: according to social science research, conservatives -- under-represented in academia and thus less likely than liberals to be "skilled researchers" -- give more charity than liberals.