Punk Chic... true the cuticle layer has to be flat but you are not taking into consideration what her hair texture is like, how damaged the hair, the products she currently uses, color, perms and on and on. All anti frizz products except for waterproof products contain alcohol or dilutives and eventually dry out the hair.
Yes, a heat resistant product keeps hair from burning while depositing deeper into the hair shaft also helping the cuticle layer lay down better but it has to be a waterproof product. Give it a try and it may open new doors.