Dismissing someone’s comments by simply saying “this makes no sense” is rather blunt.
Especially since it does make sense.
Skin irritation is correlated to irritated intestines. That’s a fact.
Of course, there are several possible causes for skin irritation. It’s like “all cows are animals”, which does not mean that all animals are cows.
In this case, intestinal irritation very often causes skin irritation (“all cows are animals”). But nobody ever said that skin irritation is always cause by intestinal irritation – that would be similar to “all animals are cows”.