Doesn't matter, slice you open dead. I wear flip flops on construction sites at times, cut with a Skilsaw in them, resting the board on my foot.Unless someone was there, no once knows for sure that they fished wahoo in their "sandals"... this could have been taken while traveling, could have pulled a couple of hoos from the rsw and posed with them at any time. They look kind of "clean" to have just caught them in a wide open bite. Hopefully, they were wearing boots or covered toe shoes when they caught them.
I don't know what your thing is but you won't make many friends with the other passengers when a trip gets cut short so the boat can head north to rondevous with the coast guard team sent to evac you. Or if a skipper moves away from wahoo fishing because the passengers refuse to follow the rules. Last trip I was on a guy was wahoo fishing barefooted and I had a crewman talk to him. Last thing I wanted was to spend hours keeping a guy from bleeding out. Some boats don't even allow anglers to hold up their own wahoo for pictures. Even dead ones are dangerous.