It’s not like the bladder is radiating heat away when it’s inside the body. Heat doesn’t just get used up, it has to go somewhere. If it was in equilibrium it would just increase your thermal mass and have no effect.
Like I said though, I think the issue is that it’s constantly moving heat away from the core to the lower abdomen where it can be radiated or conducted away.
Wow, never would have guessed that a squirrel can just chomp through my bones