Nope, Aliens never had a 4K scan prior to this release. I had the pleasure of seeing the special edition cut on the Fox lot in 2014 hosted by their home entertainment department, and they screened the best they had available - a 2K DCP - and even mentioned that they would love to someday have this available in 4K.As I mentioned in another thread, I think those people are misinformed. As far as I've always been aware, Aliens was already scanned and mastered in 4K for the Blu-ray release in 2010. Lowry Digital's special de-graining process that James Cameron was so happy with relied on a 4K workflow. So, even if this new A.I. processed transfer is based on the existing Blu-ray master, that work already started in 4K.
I think the people claiming that the new 4K is upconverted are working from the false belief that, "2010 was, like, a hundred thousand millennia ago. 4K didn't exist back then." Which is wrong and stupid.