Goldman Sachs is large enough and ubiquitous enough that it should be assumed that they are, to some extent, on both sides of every trade they recommend (or discourage).
Just because Goldman is telling their pension fund clients to avoid crypto doesn't mean that they don't have teams trading billions of it daily.
Nothing prevented GS to enter the crypto space and offer a product similar to Coinbase's.
Instead, this is what they were spending their time on:
https://www.theguardian.com/business/2017/nov/30/bitcoin-is-...