Shanks showed that he care for the new gen.
He stay true to his character; wont let anyone harm his friends.
He may have anticipated that BB will come and take the DF of Kaido, BM, or even Luffy.
That's why he went to Gorosei to talk about certain pirate.
Hopefully we will get an explanation for this.
Even if it was for Film Red, Oda will try to connect it to previous plots.