Well, "evil" here is just a very subjective concept. Tree of Life as the Universe (or merely our psyche) emanates it all, and does so in the case of polarities, that I agree with. What I do not agree with is labelling something "good" and "evil", especially an entire sephirah.
Geburah is struggle and strength. Geburah is fire - and fire destroys, but creates. Struggle is good and crises are often the purgatory. For you, fire might be "evil", but here above the Arctic Circle where it hits 40 degrees below zero in winter, fire is survival.
So when i say there is nothing "evil" in the Tree of Life, I mean that there is nothing which can so simply be labelled into either "good" or "evil", since good and evil themselves are a subjective concept. Moreover, the sephiroth are much more complex and cannot be axed so simply, nothing is just "inherently" evil, but always contains its own shadow/light side.