There are too many sue-happy people out there, and every dog, no matter how intelligent or magical, is capable of making a bad judgment call.
I have no doubt that Tyr would protect me if needed. I also know that he will occasionally make a wrong choice and alert to a perceived threat. It's my job to call him off. I can always override his choice with some basic obedience commands.
And I sincerely hope that if someone breaks into my house, she just plain stays out of the way.