Salt is an electrolyte. I used to put a pinch or two in my bottles when I was using diluted fruit juice in my bottles. I typically use more electrolytes in very hot temps and way few if any during cold whether.
As for drinking milk, I used to think it disgusting too and thought it would immediately sour in my stomach and I'd vomit it up quick. However I actually tried a bottle of chocolate milk given out at the end of an organized ride by a sponsor, and surprisingly it was refreshing with no issues. For a recovery drink, chocolate milk's nutrition breakdown holds up well compared to most other recovery drinks.
For using it while on the bike? Well I think he says he uses a dilute mix. So maybe not so much unlike the drink mixes for use on the bike that have protein in them.