Libertarian doesn’t imply seriously right wing Ayn Rand crazy anywhere outside the US. It just means libertarian. It’s a bit like how “liberal” means right wing, but not authoritarian outside the US. You may have liberal attitudes to social issues and be right wing. Like the US democrats for example. Except they’re now extremely authoritarian too.
I’ve seen plenty of criticism of Greenwald from left wing sources, but it’s mostly been pretty subdued.