Well The reason they write not to use on shaved head is if you are having sensitivity to minoxidil and if you are exposing your shaves head to sun for long time there may be irritation. Although this is not very common but if you are having sensitive skin and if you have more sun exposure you may not apply Minoxidil with shaved head. Shaved head infact makes the application easy and with direct application on long hairs can make your hair stiff and the crusting on the scalp under the hair may not be easy for you to remove.
Same way hair loss can be due to many reasons some skin conditions with hair loss may have more skin irritation if Minoxidil is applied and therefore it is best suited for hair loss such as Androgenetic alopecia ( male pattern baldness or common baldness) . Because this common baldness has some link to father or mother side genetically it is written on the information leaflet given with minoxidil that those with no family history of hair loss may not use it. Since you certainly have a pattern hair loss it is Ok for you to use it without any problem. In fact it is the right indication for minoxidil