Breaking someone's leg seems a bit of a stretch...non?
Notably absent is the term "deadly force." The general rule in all common-law countries is that deadly force is permitted only when you are in reasonable fear of imminent death or serious bodily harm. And shooting a firearm is always deadly force.
If the person won't stop then I can escalate to whatever force is required to make them stop including a broken leg or a bullet to the kneecap or even deadly force. I read this section as that as long as I have a legal claim to the property I may defend it wit as much force is required to protect it. That is how it should be. I can't start by using deadly force but if the person(s) won't cease & desist I certainly can escalate to that.