I really do believe Sony looked at Elite on the Xbox and said we NEED a space exploration style game and picked up on NMS and bought it out. If it wasn't for that I'm certain it would have been released as an Indie game at a more reasonable price point. People would still have complained about the missing features, but I think the price added to the hate considerably. (then again HG may have actually got some of those missing features out 1st time without the added pressure of fitting it in a PS4).
I can't see how that is the case. Sony got involved with HG sometime after VGX (Dec 2013) and demoed it at E3 (Jun 2014). Elite didn't release on PC until Dec 2014 and the Xbox preview version wasn't shown until E3 2015.
Did Sony buy them out? From what I've read they offered to provide development funding but HG only took financial assistance for marketing and publication.