No one would call you stupid for putting your phone in salt water, I told you I did the same mistake and washed my old Xperia Z with soap and got it broken, but when I went to service and they told me that they found soap residue in the phone, I admitted my mistake.
We sould research our gadgets before risking them to be broken. We should not try wrong stuff and then blame the manufacturer who stated clearly that salt water is a no no. Sadly, we learn in the hard way.
And no you can't compare a Casio watch that has 150m water proof rating to a mobile device that has IP68 rating. And Casio would tell you that their watch can be used in salt water, and Sony also told that their mobile CAN'T be used in salt water. It's fair and straight situation.
