Obviously, there's as many variants of libertarianism as there's libertarians, but AFAIK most of them agree that there should be no state.

I think threatening the tenant with a gun to get the money then kick him out of the flat is the way it should go for most libertarians. You'd appreciate the irony of this not being an aggression.

(there's a reason why libertarianism is almost only found in the US: it lays on the Far West myth a lot)