Hasn't film red confirmed that Shanks is from the Fearland family. I doubt such crucial info would be filler. While the plot line is filler, character backgrounds aren't.
Sure. But isn't it logical that if Kaido aims for the WG, Imu ends up in the middle and will have to interfere?
Also, what about Doffy? Doffy was in their inner circle and knows of their national treasure which would "shake the world to its core", saying that the WG could not get rid of him no matter how they tried. Unless Imu doesn't care about a criminal ruling a kingdom and having info about their secret treasures that would shake the world.
It's not interest, but the knowledge that they are a strong force and potential threat. Again, Kaido occupies the most important country tied to the void century, aims to destroy the natural order of the world, teams up with another emperor, aims for the ancient weapons and the one piece and ruling over a country that basically hosts said ancient weapon.
Yet Imu only sets example against fodder Kingdoms rebelling.
And then again, why fearing Kaido if you have god on your side. Imu doesn't take orders obviously, but it would be odd if Imu wouldn't interfere with Kaido invading said god's very own country.
