1st playthrough, indeed having no clue about possibilities during this quest, i saved him only in part due to good relations with him (after all, he's just a muscle, and being one, he's far not the worst human being doing such a job - especially in compare to Adam Smasher).
The main reason, however, is absent in the poll: i was willing to see what happened to Hanako. After dropping down, i immediatelly looked up curious "can i get back up, what happened there?", climbed up, and there he was.
By the way, what really puzzles me - is how it happened that Arasaka goons did not flatline Takemura right away, BUT then kept trying to do it. If it'd be Hanako who ordered them to back off - then attackers would not keep trying to off Takemura. So she did not. And given how attackers captured Hanako - how in hell they failed to flatline Takemura, who was right next to Hanako at the time?
I mean, imagine you're squad commander. You were able to free the "hostage" (Hanako). Wouldn't you have your team to shoot or at least capture the "hostage taker"? Something like this:
So yeah. Puzzles me to no end... %)