I've corresponded with Mary Theobald, the author of the article. While in the land we today call China, there are references to a chilled or frozen milk product..., milk faded from the Chinese cuisine so probably was not the origin of what we would call ice cream.
While an Italian doctor noticed the salt and ice reaction in the 1500's, it wasn't really widely known until a friend of Galileo "rediscovered" it in Florence, in the mid 1600's. It should be noted that Catherine de Medici was from Florence, and that may be why some folks think that Sabayon, which did exist in Catherine's time, may have been confused with what we call ice cream.
OR..., it may simply be that Sabayon was the basis for the first true ice cream, omit the liquor, and use the ice/salt method and voila, and since it existed in Catherine's time ice cream must have been there too...., Well, no, but the earliest ice cream recipes are very close to cooked custard, so I think our ice cream, is a Florentine invention, ....,
Anyway, back to camp foods.....
LD