yeah saying it doesnt work without an explanation that they can understand will never get them to understand.

As noted without something with brains like a host auto switcher, two USB hosts cannot be connected via the same time to a USB device, if you use a dumb spliting cable all you are doing is backfeeding the output of one computer into another, which including power can blow out the USB ports on the laptops (i had a backfeeding hub that blew out my USB port on a brand new MB, with the PSU of the PC unplugged the motherboard was still getting 5v as you could see the LED on it still lit up)

Not sure how much the one you listed is but something like this is cheap if they dont want to manually switch between hosts

https://www.amazon.com/Premium-USB2-0-Automatic-Sharing-Switch/dp/B001H91G4W