Comment by codex

This article seems to gloss over the hypothesis that aliens evolved under evolutionary pressure, and are thus likely to want to reproduce and expand. So no matter how advanced they may become technologically, they might still want our resources and our planet, simply because they're reproducing themselves at an exponential rate--especially if they've solved the immortality problem, which is likely. Even with advanced birth control, aliens may still want to have cute alien babies. They could chose to simulate their lives in a computer instead, likely it's cheaper to acquire a real planet than simulate one.