I think the timing was the problem rather than the route.
I think the best weeks for combined land and sea trips to Po Toi are first and third weeks in April and the first week in May. This trip was two weeks too early.
Having said that, two weeks time is Easter weekend which is probably not easy for many people and if the trip had been one day earlier, a number of people may have seen a probable HK First (Brown-backed Needletail).
Still, I don't think sea trips should be held until April. March is just too early, for both land and seabirds.