Yes, pretty strict now has been my experience since they cracked down last year on access restrictions for CCR card holders. They are sticklers for rules in Singapore, and the rules quite clearly say that access is limited to passengers leaving Singapore on BA F.
Fortunately, the new QF F lounge should be opening before the end of the year, somewhere near the D Concourse. That will likely be a major improvement over the current options for Goldies and other OW Emeralds.