Question: if coinbase is the custodian for grayscale would coinbase's 4.7% include grayscale's 2%?
I have no proper evidence, but my feeling is yes, that figure is including Grayscale 2%.
This make sanse on a legal point of view, as Coinbase said is custodian for 4.7%, so that includes the BTC owned by third party clients. Being custodian is different by being the owner (in legal terms).
Also this makes sense from a marketing point of view, where you want to appear the big swinging dick in the room.