Yeah. He doesn't kill people because of Oda, not because of his nature. He's threatened to kill people before:
**Pirates: Heheheheh!! Look at him, yellin' all scrunched up like that!!
Lookitim cryin'!
Gyaahahahahahahahaha!!
Yaaaahhhh!!!
Luffy: If you laugh at Usopp ONE MORE time,
I'LL KILL YOU.**
Oda wants to appeal to all ages, so that's why he tries to tone down or avoid killing characters if at all possible. If it's necessary for the story, then he plays it off or simply leaves it ambiguous.
That aside, though, it's a standard in most Shonen. Goku technically never killed anyone (except Piccolo Daomi, by accident). Raditz was killed by Piccolo, Vegeta was never killed, Vegeta killed the Ginyu force except for Captain Ginyu (and Zarbon and Dodori), Frieza was technically killed by Trunks, Cell was killed by Gohan, and Kid Buu was killed by Vegeta.
Naruto only killed one of the Pains and he was already dead, and Ichigo has only killed nameless hollows, which don't really count.
The point is, in shonen, the main character is supposed to be a roll model. They hardly ever go around killing people intentionally, though if someone dies at their hands, it's up to the individual nature of the character to show remorse or not.
There are exceptions, of course, such as Death Note, but it's generally the rule.