Hi there soccermom30!
I have an article here about Parental Controls on the iPhone that can tell you a little more about the abilities of these settings:
You do have the ability to enable Parental Controls on his iPhone and restrict explicit content from the iTunes Store. These settings will apply to iTunes Match as well, but only for content on your iTunes Match library that is specifically marked as "Explicit." If a song has explicit language but is not marked with the "Explicit" tag in iTunes, then it will still be available from the iPhone using iTunes Match. This advisory about explicit content tags in iTunes might be helpful to you regarding explicit tags and Parental Advisory content:
Take care, and thanks for visiting the Apple Support Communities.