Where waders can get one into trouble is that neoprene and rubber stretch and swell when filled. Water has weight, you, the surf and rivers are moving and the combination of all this and your own plus that contained water's momentum (linear and rolling or circular) can be very unnerving, cumbersome and depending on the persons size and strength almost impossible to manage. Get caught in the right rip and even with just a swim suit on you'll have your work cut out for you. The proper thing to do is swim to the side as said but water speeding out a rip at varying velocities with varying degrees of bouyancy (air bubbles versus not) and waves coming in creates a situation that many have real problems handling. With any waders be sure, doubly sure, to wear a tight belt sealing the tops closed and that's just for starts. Use a staff and steer clear of rips, longshore currents, rough bottoms, drop offs, low head dam areas and almost any unfamiliar situation you haven't handled in practice with rescue folks standing by.
Sad to hear of the anglers misfortune!