Yes, you are correct. There are non-motorcycle, synthetic and non-synthetic oils which work fine if they don't contain that one special additive which might cause a 28 year old clutch, with slightly weaker springs, to slip. Besides, this is his brand new baby girl. Give him time for the new to wear off then he can read up on the service classifications and compare bike and auto oils to find the one which works best for him.
FYI: I changed the verbiage in the my original post to better clarify this information for the next reader.