A lot of the people you mention were not liberals. You may need to broaden your understanding of political identities.
Particularly Christopher Hitchens. His earlier political incarnation was a Trotskyite not a liberal.
Fareed Zakaria was a member of the most conservative party
in the Yale Political Union.
Kanan Makiya, being an Iraqi exile, was pretty much a one issue voter and would have gone with whoever wanted to invade Iraq. However, he also, was another Trotskyite.
Also, personally, I opposed the invasion of Iraq.