When Marines attacked Hancock, her Bounty was already Updated to 1.6B,
So according to you, Marines gave Mihawk an Updated Bounty (Let's say 2.5B Bounty for example), and then 24 Hours later, They updated it to 3.6B because He formed Cross Guild? Ofc not
Cross Guild isn't an already established Organization that They joined, leading Marines to increase their Bounties, it's them who Defined what Cross Guild is, the whole point of showing their Bounties was to demonstrate it's threat,
It's like imagine you go and create such a new organization, and Brannew be like: "This Organization is Yonko-Level Threat because 3B Rayan founded it" and They are like: "Why does Rayan have 3B Bounty?" and He replies: "Because He created this Organization", that doesn't make sense,
Also, Hancock got 1.6B, it's obvious that Crocodile wd also receive comparable Bounty, it's not like They gave him 1.7B & then because of Cross Guild, They were like let's increase it a little bit; I mean if Doflamingo comes back, you will be shocked if He gets 1.9B without joining any Organization? It won't surprise anyone tbh