How come the western world supports the anti-gaddafi if some of them are al-qaeda?

I know Gaddafi is crazy and evil dictator, and I support democracy than dictatorship but if Gaddafi lost and step down, which the western world wants, isnt there any possibilities that Al-Qaeda Organization in the Islamic Maghreb and other extremist can take over libya instead of pro-democracy rebels? I know American Revolutionary War hero Francis Marion was a terrorist. South Africa's President, Nelson Mandela, was a terrorist. Sinn Fein was at one time, totally comprised of IRA terrorists. Former Israeli President, Menachim Begin was a terrorist, as was the PLO opposition leader, Yir Arafat. Terrorists who are later freely elected to public office, often become very good, peaceful, and practical leaders. But I think AlQaeda is different, because one of their goals is to destroy america and spread islam with force worldwide. I think Gaddafi is better to rule Libya than AlQaeda, right? please give me some proper answers thanks. And please answer the question and not adding other info okay