Yes, he managed to partially turn his head first, but there is no question that without a mask his sneeze would have covered a much wider radius...including the customer standing directly in front of him.
Regardless of how difficult it is to prevent viral transmission in a sustained hospital setting, there is no question that even a minimal face covering reduces transmission of in common everyday situations like the one I described above.
Common sense seems to indicate that masks should help. But how much they help, and if it is enough to make a difference can only be seen by looking at actual data.
Soon we will know how much of an effect masks have, since in many locations the overwhelming majority of people are wearing them.