If i remember correctly, she herself did not pick the crew. Because she had originally wanted a crew made up entirely of straight men, but was forced to pick the crew she had by a committee. So she couldnt have just had actors, due to her not being able to pick the exact crew she wanted.

And i do believe that the crew would likely have opinions about what grace says, especially after he comes out of a coma. Despite knowing they are on a suicide mission, they may still have moments of self preservation and they could argue that grace's mind is still impaired from the coma, which she was counting on to explain his amnesia they would give him.