Either he has mods enabled, has edited game files, or has a corrupted installation.
In the latter two cases have him do a full clean re-install:
- move any valued save games elsewhere, and user empire designs.txt from /Documents/Paradox Interactive/Stellaris/ if you have made any custom empires or races."uninstall" in Steam-Stellaris
- manually delete both the Steam/SteamApps/common/Stellaris AND Documents/Paradox Interactive/Stellaris folders - **In particular you need to make sure there are no files or folders left under either the Steam Stellaris or Documents Stellaris locations, before installing again.**
- re-install game in Steam, run a Steam Verify when done.
- add stellaris.exe to the exceptions list of your antivirus app; ESPECIALLY if you have Windows Defender, add it to the Ransomware "Apps Allowed Through" list.
All the best!