I smell a desynch. I'm pretty sure that Eba is not aware that an operation might save him permanently, rather that she thinks that it might stave off the inevitable a bit longer, and under THIS assumption she'd be perfectly right - it's Kazama's decision to make.
It's simply against her disposition to stay around Kazama letting him die, if she knew there was an alternative. Almost certainly Kazama was less than truthful, indicated by his displayed embarrassment. And Seo wouldn't have underlined that Kiyomi doesn't know Eba if it weren't important.
In a way, Kiyomi reminds me of some readers
... quick to jump to conclusions, quick to condemn without knowing all facts, quick to judge and mete out punishment. Another oh-so-Seo character.
Menty's crystal ball prediction:
o Eventually, Eba will succeed in pushing Kazama to take the operation after all by promising him not to leave him afterwards.
o Operation succeeds
o Eba heartbroken
o Haruto heartbroken
o Someone (probably Mishima) will have to smash some sense into Kazama to stop being selfish and release Eba