Whatever the case, it never made sense for Who's-Who to have gone to Elbaf, all the way up to the Castle, and then leave with the fruit only to be carrying it around with him for an entire year, much less for Shanks to take an entire year to get it back ever since the day it was taken from the castle he was in.
Knowing.. from where the Hell Cp9 got the Nika DF.. it is one of my fav misteries.. always wanted to know that...
Also i guess when Gorosei sayed.. WG in 900 never could get a hold of the fruit.. like if fate or somehow Reality itself got warped and twisted by the same fruit to prevent it; i guess they refer as to Being able to reach Mariejois.. and lock it forever in a basement.. like the Hat... thus cropping away forever the chance some asswipe eat it.. reach G5 and become a treath 4 them.. so just being able to be capture in a Ship, momentarily doesnt count.
Now this is a nice question for you:
Did Shanks knew they were transporting a DF? that Df in particular? or he just attacked the ship.. cause well.. he is a pirate and maybe they were on his territory... and Fate did the rest..
If we GO by the "FATE" and "Own will of the fruit" Path...i would like to think on this timeline:
1)Cp9 got the Nika from god knows where...
2)Shanks Have no freaking clue about that-- just see a CP9 ship attacks, and he realize they got a DF. (maybe not even knowing it is the Nika one) ; i guess not cause in the bar,, he seems to know it as the GOMU GOMU.. or was playing Dumb
3) HE NEVER EXPECTED THE FRUIT TO BE CONSUMED BY SOMEONE,,Like Luffy on that Bar,, (That being FATE / DESTINY/ Own will of the fruit 100% in Play)