This sounds disingenuous. How does your grandma fare on Windows? Can your grandpa even navigate Linux? For all I know, your grandma could be a HN user and your grandpa a plumber.
She's significantly worse with technology than he is. Neither could tell you what an operating system is. These are exactly the type of average people that supposedly Linux isn't good enough for.
My grandma does this all the time from her Linux laptop. My grandpa needed help getting it to work the first time under Windows.