The Mac version, PAF/Family Records 2.3.1 is not compatible with the current MacOS X and has been discontinued. The data files are not compatible with other Mac software. To use the data in other software the data MUST be exported as a gedcom file (or a series of gedcom files if he has multiple PAF files).
You might want to check www.macgenealogy.org for information and reviews on current genealogy software for the Mac. PAWriterII is free and looks interesting, but I have no personal experience with it. Reunion is highly regarded, but fairly expensive.
If the new computer also runs Windows (e.g. via Boot Camp or Parallels), he can use the free Windows version of PAF 5.2. But even in this case he will need to export all his data in gedcom format first.