It's not really about GPL violation, it's about laziness. There are plenty of things Samsung could have done to work around the GPL without opening a massive hole. For example, they could have created a user-space server, which either mapped /dev/mem directly (as root, and then dropped permissions) or mapped this special device but was only given permission to do so after some cryptographic check by the kernel: a simple hash of the text would have sufficed.

This is just a dumb mistake, on par with the original Android G1 release which ran everything you typed on the keyboard in a root shell.