Guess it's a matter of balance. What would the AS add for all the players (and there are a lot of them) who are not interested in Greenpeace, or even directly dislike them? Would it be enough to either sacrifice one of the other ships in SSE or delay the launch of the game?
Maybe it will come up as a Shipyard offer if the whole Greenpeace direction seems to interest the players after launch.
On a side note, we do have the Elbe in SS08 and hopefully in SSE, another (ex) Greenpeace ship, then sailing as the MV Greenpeace, serving for 15 years between the sinking of the Rainbow Warrior and the acquisition of Esperanza. Greenpeace (the ship) also operated in the Antarctic as well as many other places around the globe, taking her many full turns around it.
Personally i think GP is well represented with 3 vessels already (Esperanza, RWIII, Billy G.).