The engine has ball big end bearings and contains oil passages and ports to ensure needed oil keeps the bearings lubricated. Ball and roller bearings do not need a high pressure oil film to live like babbit type bearings do. Bearing failure in XS650s tends to be related to disuse allowing rust to form rather than wear during use. With reasonable oil changes the bottom end often goes 60,000 miles or more between overhauls.
The manual shows a lubrication schematic and I swear i have seen engine oil distribution art also but can't place my finger on it. So... who was the expert who "informed" you that it's splash?