Attacking Ragnar would not be that frowned upon given the circumstances.

If Denial stays put and Blake gets killed, then this entire situation would actually look incredibly good for the marines. People would be clamoring to go and kill Ragnar themselves. Two yonkou commanders are down, and 6 yonkou executives are also down. One of which has decided to rat out his old friends.

We as an audience and the players themselves know how important those who were lost were, but most marines will just see them as two lieutenant commanders, a wolf, and maybe a random officer lower down, and compare the losses on both sides. If anything, Acceptance made things harder for his side, because he took out somebody from the equation that would have made them more feared.

Now it looks like two Section members got defeated at some podunk naval base. People would probably confabulate that Powder was only in charge on an interim basis, because Gus died and they couldn't find anyone to replace him on such short notice.

So marines would be powerscaling things and say something like: "Yeah, if we just get a bunch of vice admirals together, we could kill this guy in just a few hours."

But let's say that the gorosei secretly want Ragnar as one of the yonkou so that the blue blood can continue to flow. They somehow stop the marines from engaging any further. Then there are still going to be other yonkou and bounty hunters looking to kill him and his followers.

So November probably isn't done launching attacks on marines. It is imperative to the survival of his organization to not look weak, so I think he might organize the deaths of several vice admirals to both show that the Ragnarok pirates can't be defeated that easily, and to also show that Damian's crew are very exceptional marines.

Also, Denial and Blake already sort of declared war by being in Paradise. At that point, they might as well have just been associates to the main crew.