[metaphorm]

the basis of the riddle is the widely held assumption that the surgeon is is male, which is more or less justified based on demographics, even if it is a biased assumption.

evidence: https://datausa.io/profile/soc/291060/#age_gender

now, it's an interesting riddle because it exposes the way we often generalize from demographics even when there are reasonable contextual clues that our generalization isn't accurate.

however, I don't go so far as to call this a prejudicial kind of bias. I don't really think that the tendency to generalize from observations is unreasonable or necessarily connected to prejudicial or exclusionary actions.