I'm not sure what would be "pseudo-science" about it, but it is as legit as it can be. Reconstruction of a face from a skull is possible, but the goal is not to create an image that's indistinguishable from a hypothetical photograph of the subject. Rather, the intent is to form a general idea of what people of the time period would have looked like. Facial reconstruction is guided by current understanding of anatomy, musculature, aging processes, etc. Muscles and skin are attached to the skull based on modern human and primate anatomy, so what we get is a plausible representation of what someone with this exact skull shape may have looked like. Like with the dinosaurs, we cannot be 100% certain what the superficial exterior features looked like exactly. But, unlike with the dinosaurs, we know neanderthals are very closely related to modern humans, so we have a much more reasonable base to start from, as we can assume their facial muscles, skin, hair etc. would be similar to humans, but with different proportions. Plenty of real science goes into the process.