You're correct - that is contradictory. I've corrected the problem statement to be consistent with actual baseball rules. i.e. that the runner on 2nd will not advance unless he is 'forced' i.e. a runner on first pushes him.
Thanks for spotting that.

Could you offer me an example? I'm unsure how this could be exploited.

Fair point, have added an explicit test.
Added additional random tests with better distribution i.e. a S happens more than a hit etc

Thank you, again.
Very specific edge case caused by a typo. Added as specific test.

Thank you. Resolved.