Taipei arguably isn't. Its city limits do not extend to the coast. (You could make a case for the Tamsui river being tidal at that point, and so it counts as "ocean" but the quiz doesn't make similar exceptions for other capitals on tidal rivers - notably London UK and Seoul ROK - so it's fair to say that tidal rivers don't count.)
However you're absolutely right about BSB Brunei, Djibouti Djibouti, Luanda Angola, and Freetown Sierra Leone. The absence of these countries is... puzzling.
However you're absolutely right about BSB Brunei, Djibouti Djibouti, Luanda Angola, and Freetown Sierra Leone. The absence of these countries is... puzzling.