Or they decided they didn't need to make a public get well statement has any other royal member done it? No they haven't so why would they? Why only them?
They issued a statement denying they had commented on the photoshopping, seeing as they were making a statement about the situation and the controversy, I think most people would have added a kindly get well soon line to that statement.
They are the only family members who have made any statement about it it, none of the others family members have.