What a fantastic chapter. Now I can't wait to hear the soundtrack for this.
Interesting how Garling is more open to Imu leaving. Maybe because he's new and has experienced more of the modern threats?
I say a bit of that, and Garling's is taking advantage of the circumstances. We don't know how long the Original Five Elders have been in service, but we know that Saturn has been around for at least 200 years. It may very much be possible that they have been with Imu since the beginning; however due to the longevity of their position and whether they witnessed Imu establishing the World Government, it leads to the revering Imu to the highest order.
That's not to say that Garling or the other knights don't revere Imu, as I imagine that they do. However, it's somewhat different; in the case of the original Five Elders, they revere Imu like a deity or God whom they must serve to the absolute degree. However, in the case of Garling and the other knights, they likely see Imu as simply a figure above them; destined for worship, but not irreplaceable. We even see a bit of this with Sommers attitude of putting the blame on Imu if the mission had failed; that's not something any of the original Five Elders would've even considered. Now it's always possible that Sommers is the exception, but I don't think that's the case. In fact if I recall, when Vegapunk had sent out his message, both Garling and Shamrock were amongst the individuals pictured who had the chance and ambition to find One Piece and change the world, showing that Garling and Shamrock both have noticeable ambition.
As for Garling's attitude towards the Five Elders; I imagine he's playing the smart game of taking charge. He already quickly established himself as their equal, and is now pointing the direction of their efforts. Even his mentioning of Shamrock quelling the situation merely brings the achievement back to Garling, in which he could opt to take charge of the Five Elders. It also helped that the Five Elders have already 'failed' when they both allowed Luffy to escape, Vegapunk's broadcast to go live, and for Imu to have suffered pain from Joyboy's haki.
Sure, they secured York, but as we can see, the hunger situation (which was escalated due to the broadcast) has worsen to the point, she can barely work efficiently enough to provide the Motherflame as needed. So unless drastic action is taken, the situation won't improve, hence Garling's action of taking charge can be brilliant here. It especially helps his case when Imu's own objective aligns with Garling's words.
I assume the blood from his mouth + the elders' (minus Garling) concerns about Imu leaving means that he's on a time limit so maybe the damage caused won't be too severe but... do your best surviving, straw hats!!
Honestly if not for the blood and the obvious concern that the Five Elders have; I'd have said that this was checkmate for Luffy and the rest. But since we see Imu's current state, then it's definitely safe to say that whatever threat Imu may pose won't last forever. So it's either a option of weathering the storm or probably destroying the circle to send him back. Either way, they're in for the biggest fight of their lives.