This.If Doffy's organs never recovered, then Doffy would have died when KKG knocked him out since his strings would deactivate and his organs would fall apart. So Doffy's organs were fully recovered before KKG knocked him out. Just one hit from Bellamy had Luffy spitting out blood, so Luffy would have been very weakened after being a punching bag for Bellamy after 15+ minutes (and he also wasted some Haki). And yes, it was 15+ minutes since their fight started before Hajrudin defeated Machvise and it ended shortly after Zoro defeated Pica. So unless you think all of the Executive's fights lasted less than a minute, Luffy vs Bellamy would be around 15 minutes, if not longer. Besides, Oda was clearly trying to portray Luffy and Doffy as being about as damaged as the other since he had both Luffy and Doffy comment that the other person's health was bad on the same page.
Also, GK only affects the organs close to it, and Doffy stiched his organs back together after a few seconds.
Sometimes people don't realize how intentional certain things are in manga or anime.
Oda was clearly portraying that, just like you said.