It would be great if LogMeIn connections to Mac had the ability to view if the keyboard and mouse was currently in use or not and how long since it was in use like in Windows. There is no way to tell otherwise except for some custom services/scripts. There is no reason for this not to be implemented. There is a solution on stack overflow which supports this: https://stackoverflow.com/a/2262587
You can use CGEventTap which will execute every mouse movement and can log it with NSEvent. You can even just use NSEvent and poll it manually. What is your problem with not adding this?