[Trailerpark Badass]

However, I would like to know what Hitchens means by "reaction" and "reactionary." Maybe someone can enlighten me?

In the socialist lexicon, "reactionary" is a synonym for "counter-revolutionary," though I think Hitchens is using it here to describe anyone who supports ideas which run counter to the goal of individual freedom.

[Sam Cree]

"though I think Hitchens is using it here to describe anyone who supports ideas which run counter to the goal of individual freedom."

Though individual freedom is always compromised by socialism, of which I believe Hitchens is an adherent.