Despite some fairly recent changes, Gold was planning (only a few months ago) to keep its presence on Freesat:
http://www.mygoldmusic.co.uk/Article.asp?id=486495
If it's suddenly disappeared it either just a temporary glitch or This is Global (which is the company behind Gold) has found that the advertising revenue generated by the station's presence on Freesat is less than the large amount of money that it has to pay to broadcast from the Astra satellites.