Actually it's not as bad as you'd think... Turbulence in a situation like that a trivial factor, the tendency is to either stay in the flow (where your relative velocity is low) or get kicked out of it. Unless you're trying you're pretty much guaranteed not to stay at the interface of the prop wash.

And aeration from a point source like that is very much a function of water velocity, and the air bubbles tend to rise pretty quickly. So if you look behind a motor boat you might see a long trail of bubbles but the length is mostly because they get pushed far out, not that they take a long time to rise

With a pfd, if you had the foresight to hold your breath, I'd say it's pretty much a guarantee that you'd survive. So in context is just a question of whether they got caught off guard and got unlucky with their breath, or of they got disoriented.