I would think the same caution would apply to raw milk. With some acute GI problems like very bad diarrhea, the uppermost cells of the intestines can slough off. The cells that replace these initially frequently don't have the same amount of lactase, the enzyme needed to digest lactose. So the lactase sits in the gut and draws more water in, making diarrhea worse. Raw milk would have the same levels of lactose as pasteurized milk, so I think this problem would still apply.