"Think about what a white man would do" seems completely ambiguous to me. It's not a clear way to communicate. It would be better to follow up "I see you're hesitating to take credit for your work" with specific examples of what she might be able to say. Or you could give examples of behavior that people she knows have exhibited.
Even if "what a white man would do" wasn't emotionally charged (and it is), it's not a good way to make the point.
Even if "what a white man would do" wasn't emotionally charged (and it is), it's not a good way to make the point.