Robin was Not a Pinko
I'm enjoying the analysis of folklore, but I don't think it's a fair assessment to say Robin Hood was libertarian unless you're making the argument that property only belongs to someone if they're able to defend it.
Libertarians would argue that property belongs to whoever first claims that property, and so even though it stretches that argument somewhat - because it would be claiming an unknown quantity of deer - there's no reason why a king couldn't claim every one, especially if they were on land that also broadly belonged to the kingdom.
As far as taking money from clerics, or whoever, their money belonged to them. Just because someone lies about not having money to give away, doesn't mean that money belongs to them any less. He convinced them that their guilt justified the theft.
The Robin Hood you describe is a power-tripping anarchist, more than he is a libertarian.