M.D.
My son also didn't want to put his face under water. The swim instructor was so patient with him, but did dunk him on the 2nd or 3rd class because he just wouldn't do it. Once he did, he was fine. Now he swims like a fish. That was 2 summers ago. We need him to tread, and then he will be good to go.
That is also what they do to babies. They take them and put them face first into the water and scoop them up. It's normal and fine. It's how babies and kids learn to be okay with the water. It's better to do that then to have them fall in and not know what to do.