"meant to survive rain storms" doesn't really mean the same as "meant to survive flooding", especially not "meant to survive flooding with salt water". For example, a car survives outdoor weather year-round, but you probably wouldn't want to buy one that was submerged in a flood zone. This plant seems to be floating, though, so they stay above water regardless.
Putting aside the salt water, you'll also just have lots of crud and debris on the panels if they get over topped, which then requires cleaning. Unless the rain in that area is strong and consistent enough.
Seems like a weird location to me, but what do I know.
(direct link to image: https://assets.bwbx.io/images/users/iqjWHBFdfxIU/iy93Jvbye2e...)
Solar panels are meant to be water proof, after all they are meant to survive rain storms and melting snow and coastal weather.