If I’m interpreting Kuzan’s dialogue here correctly, then SWORD agents aren’t technically still Marines. They’re still loyal to the organization and whatnot, but they aren’t on the books like other Marines.
Are SWORD agents able to increase in rank?
Coby’s the same rank that Axe-Hand Morgan was way back at Romance Dawn, but he’s clearly considered a big deal in-universe. And for that matter, none of the other SWORD agents are at a rank above Rear Admiral, yet they seem way more competent than guys like Yamakaji. So did the SWORD agents get their official ranks frozen when they joined SWORD? Since at that point they’re not officially part of the organization anymore.