No, He just wasn't just not hydrated enough. He failed to drink enough fluids, and probably was dehydrated before he even started out.
Everyone has enough salt in their system, they don't need more just because they sweat. In fact most people these days have far too much salt in their system which is what causes them to retain to much fluids, have high blood pressure, bloating, and other nasty stuff.
We all need a small amount of salt in our system, but too much is also a deadly poison. We get more than we need from the food we eat, and no amount of sweating requires us to take more.
There was a time when the army thought we needed a salt tablet to help us retain water. But that was proven false ages ago.
If dehydrated people needed salt, why do you think people lost at sea die when they drink sea water?
One summer when I was 13 my brother and I rode 1000 miles on bicycles through the Ozarks in three weeks, averaging about 50 miles per day, with bicycles loaded with full camping gear. We usually drank 2 to 4 gallons of water a day. By the end of each day we’d be covered by a quite easily visible layer of salt crystals. To the point where rubbing the hand across an arm would produce something resembling a snow shower.
We discovered pretty quickly that we needed extra salt or we’d get cramps. We tried salt tablets washed down with warm water and found out even faster that induces vomiting efficiently.
We wound up putting unreal amounts of salt on our food, as in 1/8” of salt on a hamburger. Worked great. Oddly enough, didn’t taste overly salty. I figure that was the body letting us know what it needed.
So don’t tell me those who sweat a lot don’t need more salt.
I realize these were extreme conditions.
Boy are you confused!
Your cells cannot hydrate without adequate salt, and that means sea salt, not the poison from the grocery store.
And no, sea salt cannot poison you in any kind of quantity that you could conceivably ingest.