The killing would have occurred even if we stood back and watched from the sidelines. You must remember that inaction embolden Hitler, which resulted in the deaths of millions of people during World War II and inaction resulted in the deaths of thousands of people in the Balkans.
Lybia was invaded by a foriegn entity of whom Qaddafi would have crushed within weeks if not for night and day air campaigns run by NATO. No where near 30,000 would have died. And now Lybia is run by people who make Qaddafi look like santa claus. But hey at least they have a nice new IMF building, while the rest of the country is in ruins.