Olive oil is wonderful for unwanted curly hair. The biggest complaint I get is when people get a perm and it turns out frizzy and after using the olive oil shampoo the curl is so relaxed that they get upset because they want those curls back.
If you use those products to relax the curl in your hair, then yes, you won't need to use these products again, including conditioner. I use mousse and gel to give my hair body and hold the curl after using the curling iron.
Many of my customers that have fallen in love with the olive oil shampoo are African American and just love the natural relaxing effect the shampoo has on their hair, now they don't have to use chemicals to straighten their hair.