Well... speaking as a retired marine rescue and auto extracation trainer, I would have done that capsule interaction somewhat differently. The first thing I would train is to assure stability before doing anything else, most certainly including not opening a hatch. And they bagged it open, so it could not even be closed again if the water got rough. Obviously, there was difficulty getting the flotation ring fitted to the capsule and inflated, but it's the opening the hatch, and then preventing it's being quickly closed if needed which caught my attention. It left the astronauts very vulnerable for much too long...
Liberty Bell 7 resounds in my mind, and Gus Grissom was alone, and got out with adequate safety - lucky!