I'm not really going to debate the moral issue, as there are two sides. But, some of the posts seem a little one-sided. I think before answering the moral issue, you should ask yourself this: if someone came into your home while carrying, do you feel that they have an obligation to tell you?
Absolutely not. Now if they make me aware of it by taking it out, handling it, or otherwise doing actions I believe are not suitable during thier visit that make me uncomfortable I would ask them not to return with a firearm. From then on I would know I do not want that individual over with a firearm, and may ask if they have one if they come over in the future.
If they lie and I found out, they would be prohibited from returning, and charged with trespassing if they did.
The person that wears it like they do a belt and makes it as much a non-issue as the wallet in thier pocket is not a problem.
They are as entitled to self defense on thier way to and from my place as they are to breathe.
Considering the SCOTUS has ruled the police have no duty to protect any individual, multiple times, I feel any rule which limits the ability of citizens to protect themselves is a violation of the principles of our nation.
I feel anyone that imposes such rules on an individual should be liable for thier protection and for any failure to protect said individuals who do not have the option to provide for themselves due to the rule.
Whether it is a state, city, business, or private individual.