i mean he knew that guy wasn't transformed completely. It was THE perfect moment to throw off that sc@mbag, yet he chose to have a conversation and got bitten. now the poor girl lost her father.
It was an unnecessary drama at the end. they could've survived easily and led to a perfect ending
This is a genuine problem in the film. Of course one can always make excuses for imaginary characters, but Sook Woo (fund manager) had seen enough to know exactly what was going to happen and how quickly. Anyone should have known that the businessman in his confused, feverish, weak state would be easy to knock off the train. I think the director wanted the fund manager to be bitten and die for his own ideas of how the film should end.
shareRight -- he could have easily gotten rid of that guy before he fully turned. The guy was a jerk to begin with, then he'd become a zombie jerk. Why wait? Idiot...
(no need for spoiler alert...)