If the phone came through a different carrier/service provider, they could have had that option restricted. Happens all the time. It could also be that the carrier/service provider, or the account type he has, has a restriction on this option.
Have they tried, instead connecting the phone to the computer via an actual cable, to connect it wirelessly. Using the phone as a hotspot?
If it is at all possible it would be done this way...
- Go into "Settings" and in the "Wireless & networks" section tap "More".
- Now tap "Tethering & portable hotspot".
- For "Wireless Tethering" tap "Set up WiFi hotspot"
- On this new screen you will see options for a "Network Name", "Security", "Password" and "Network Band". You can change them or keep them as is. It is really up to you.
- Now you would just need to search for the hotspot by name using the second device.
NOTE: While a WiFi hotspot feature is built into Android, some service providers/carriers, especially in the United States, hide it. You would then need to see if you can locate an app that you can install to help with this.
Now if this won't work either, then I would bet it is the carrier/service provider that is restricting it. That one, no one can change but them.