http://www.apple.com/legal/sla/macosx.html

His friend, is violating the Mac OS X License Agreement, specifically the restrictions Angel to use one copy of the Apple Software, (b) to use it on a single Apple-labeled computer, (c) not to lend or redistribute the Apple software.

Since his friend failed to comply with the License Agreement, his rights under the License terminate automatically so essentially he is running an unlicensed copy of Mac OS X now too.

Nagging about piracy may be questionable, but condoning piracy is unacceptable.