Without knowing most of the details, I admit, this sounds a bit weird. Procedural generation is precisely the opposite of random: procedural generation is deterministic and fixed; once a seed is given to generate a certain terrain (tiled or not) if you return you ll find the same terrain. Otherwise it’s not procedural, but just random generation.
Either way that does not seem to contradict the claim that you can explore a full planet, even if all locations are randomly generated every time you visit. Won’t be very immersive but hey, we have Elite for that.
Assuming that the same seed is used every time! FDEV certainly does that with their planets, but that's not strictly necessary, procedural generation is used for creating realistic looking terrain without spending the time hand crafting, or cities, or forests or etc, but just because you can use it to craft the exact same terrain every time you visit a particular locations doesn't mean you have to do it that way.
I mean many games that use mazes use procedural generation to create randomised rooms, it's a minor nitpick but an important one, procedural generation is in fact a special case of random generation, you can't predict what you will get until you run the seed. I mean you could use a completely random algorithm to generate the ground surface, which would be bad because your levels would be all over the place, but the moment you put in parameters to tell the algorithm that each edge pixel of a tile tiles should be the same level as the all the neighboring tiles around and each pixel should be no higher than a pixel above or below neighboring pixels you have a procedural process, sure a pretty basic one and it would probably be as boring as anything but it is procedural even though most of it is randomly generated, so procedural is in effect a special case of random generation.
Of course not everyone will agree, and I expect the SF devs will use the same seed for a given tile to give the same result, but I don't know, got to wait and see.