I wouldn't do it, there's no justification for it. Some people might think there's a benefit in added lubrication of the valve train etc, but that's unlikely as diesel fuel does have some lubrication ...

Q: I recently was gifted a 1979 Negrini moped. It has a 49cc, two-cycle engine. After some extensive cleaning, it appears to be in good condition. The owner’s manual calls for the gas-oil mix to use ...