Hitchens did presage the militant turn that many former peaceniks on the Left have lately embraced in the name of anti-fascism. He saw militant Islam as being violently, totalistically--fascistically--anti-Liberal. So he threw in with those who were in favor of taking the fight to that enemy.
To identify his new-found allies as the 'lesser of two evils' would have been, for Hitchens, an exercise in the kind of vapid, cliched, weak-kneed rationalization he detested above all else. He had to be fully committed, whatever position he took.