That is very sad. I hope it had nothing to do with his choice of wading boots. Not that it really matters now to his family.
It just happened to be the second or third thing I thought about. I've never thought about the upside-down wader belt problem...I can see how that could happen if the air traps the fabric tightly against the belt. When fishing around deep water, it would be a good idea to have a self-inflating PFD. I used to use a float tube a bit, but got rid of the thing because I didn't trust it not to kill me, and I always wore a PFD that would inflate with a tug on the cord - of course, if you fall and hit your head and it knocks you silly.....
there is risk in everything from walking to the mail box to fishing to hunting big game....live every day as if it were your last.
RIP to the fisherman, and prayers to his family.