Good advice, and then then he'll need to import all of his music into it from his NAS (with iTunes set to copy files into it's library). I assumed there was a reason it was on NAS (more music than could fit on his MBP).
If carrollf wants all the music in the library, you're absolutely right. If a selection of it is OK, then iTunes Match should manage it ok.
The idea would be that all the music is available (assuming you have a network connection) and that it will download the music as it plays through it. For instance, I've got a MacBook Air with not a lot of storage space. If I want to listen to Bing Crosby, I can either start playing it (in which case it will start downloading as I listen to each song) or I can select the whole playlist and ask it to download. Since I'm in hardcore Christmas music time right now, it won't need to download my collected works of Billy Joel. But if I get in the mood for some Stormfront, I can select that and iTunes Match will bring it down.