As the name implies GitHub desktop is a more streamlined GUI that made for both experts and novice users keeping simplicity in mind.
By design, our operating systems are programmed to treat external devices (like USB) as it will be accessible indefinitely. It may not harm if you pull out the USB if it is only reading data.
Everyone tends to share a contract, agreement, etc with a client or an employee for confirmation but expect that no changes could be made by them. Can we prevent changes to a Word document anyway?