Edit: Nevermind, I mistook the Construction Requirements of Tree Seeds to mean that they could only be crafted under those conditions, when in reality it meant they could only be constructed, or 'placed' under those conditions. I can actually make Tree Seeds anywhere!
Converting regular wood into tree seeds is a Nauvis-locked recipe, which makes cultivating wood using the space cultivator somewhat tedious because it means the space platform would need to regularly stop at Nauvis to offload wood when seed stock runs low. Of course, there's very little reason to even cultivate quality wood, and even less to bother doing it on a moving space platform in the first place, but would it be possible to make the Tree Seed recipe planet-agnostic just to make it more convenient for those insane enough to do it anyways?