What timekiller said: It is your PoV, so if you play Durge, that is Durge - and that doesn't make sense.
Its not only Durge. Where would that ship have picked up Astarion? Or Karlach? Wyll?
The latter two only boarded after "you" were tadpoled during the hasty escape during Avernus. And Astarion would be in Baldurs Gate (not the city in the cutscene), only come out at night and hard to move without being tadpoled first thanks to his condition.
And as the ship had a specific, high risk/value mission why would the drag untadpoled spares along?
