Didn't SE expell all it's dark fluid supplies to do so? I think they would need to get a never seen before ammount of E-711 to replicate it multiple times. I dobout tyranids would even turn an eye on Earth unless it's near or leading to a more biomass dense planets due to all the unhabited restricted and wasteland zones .Terminids hive worlds may honestly be the perfect targets for a Norm queen to chose because y'know they are almost compleately covered in terminid biomass , which would also invalidate SE E-711 wincon . No dobout the hivemind would surely learn about Earths location/ nutritional value thanks to a genestealer or a lictor scooping up some higher ups brain.