He wasn't just carrying it around the house, he specifically armed himself to answer the door when the deputy clearly identified himself.Carrying a weapon in one’s house is not equivalent to carrying on openly in public,
Both parties made mistakes in this tragic encounter. It cost one his life, it may cost the other his freedom or job.
The Constitution supports his right to be armed, period. This means that once he is armed in his home, he can cook, use the bathroom, and even answer the front door while armed because it is his constitutional right. It's absurd to think the Constitution implies that one can't do anything else while being armed. The Constitution does not support an officer shooting a citizen for exercising his constitutional rights no matter how strongly you feel about it.