Consider an example using the Fourth Rule of the Earth:
For instance, if it is late at night, and a person is unknowingly overstaying his/her welcome at your house, you would not be treating him/her "cruelly" by saying "listen, I think you should be going, it's getting late".
If, however, you have a person over your house who's causing trouble, making a mess, being loud and obnoxious with no consideration, then it would only be wise to say something on the order of "you're in trouble if you don't get out right now."
(The very best thing to do is to not invite people like this in the first place.)
The Rules of the Earth all boil down to using good judgment, and knowing who you're dealing with. And, like previously stated, there are shades of grey in each different situation one may find him/herself in.