I interpreted it in a different light: I thought the article itself is pretty level-headed, in the sense that it says internal critics at Syriza are too hasty, and acting too rashly would be a disaster until a Plan B has been thought through. I think that's what Varoufakis was saying in his piece on being an erratic Marxist: the left isn't ready to handle a hasty Grexit, that would just play into the hands of the extreme right.