I mean, Gaban's situation lasts like 10 seconds? Blud just saw a sad future, got shocked, surrendered in a desperate attempt to save Colon, then got stabbed right away. In his mind he probably thought "If i hit her, Colon is done"
Neither of the other guys (Rayleigh, Garp and Co) managed to see a future where the hostage is killed, to the point they gotta make a decision in a matter of a few seconds, or less. If Rayleigh had seen a future where Boa is killed if he jumped Teach, would he still do it? And thats because Boa isn't even his literal daughter, we can see how much Colon meants to Gaban.
For me this is the thoughest hostage situation in the manga, and props to Gunko for being smart and not wasting time as well. As i said, she had nothing to lose other than getting chopped