Sugar (sucrose) is soluble in water and pyrimidine (C4H4N2) and it is not soluble in hydrocarbons (gasoline). This suggests that sugar granules in the gasoline will accumulate and mechanically clog up the small orifices in carburetors and injectors and/or the sugar will dissolve in what ever small amounts of water it encounters in the fuel tank or fuel filters and form a thick syrup which will also will clog up the very small fuel atomizers. So even small amounts of sugar the gasoline will eventually be accumulated and clog up the small orifices!
I have heard the only way to correct this is a complete rebuild, overhaul, etc of the engine, carburator, and fuel delivery system.
Insurance will cover this if everything is well documented AND you have Physical damage. You might want to check with your insurance agent to verify this, depending on what was said.
Document the comments stated and by whom. THEN, if anything does happen, the authorities and possible the insurance company will go after them for reimbursement of any damage.