Because the client is >55 in age and isn't a fan of change. They want what they are used to. Other clients who are more open to learning definitely and have in the past gotten linux. Huge fan of using it for bringing life back to old hardware. Some clients are however very abrasive towards the idea of a different OS/Interface/Change.
Your elderly client made a smart choice using MacOS. Elderly using Windows were not given a choice to not upgrade to Windows 8, this forced upgrade was a crime against the elderly, many of whom suffered in silence.
