It's not on the official list (unless you can prove that it's Formula SLX, which is on the list), but you can buy it at my VW/Audi dealership. If your dealer sells it, I wouldn't worry about it.
VW 502.00 approved? Technically, an argument could be made that GC is not; BUT, you will search in vain for ANY documented case where VWOA has denied warranty coverage where GC has been used in a vehicle where a VW 502.00 rated oil is specified.