There's nothing wrong with law enforcement investigating reported suspicious activity. Looked at from the LEO's point of view, this could have just as easily have been an armed burglar and they need to take certain precautions, to protect themselves and to do their job protecting the public. When guns are drawn is not the time to start arguing about what constitutes a violation of your civil rights. If necessary, that can be sorted out in court later. Complying with LEO requests lets you have your day in court, if needed. "I know my rights, and I don't have to ........." is likely to get the heirs to your estate their day in court. But once you have de-escalated the situation, exercising your rights to refuse to be searched or to let your home be searched is perfectly reasonable. And I think most LEO's, if it is done in a calm and polite manner, would understand. And if they don't, still remain calm and polite. The worst that can happen is that they search anyway. And if you don't lose your cool, you're almost guaranteed to win in any subsequent court fight.
I have known many LEO's. The vast majority are great people who genuinely want to help the public. However, since the majority of their time is spent dealing with the less law-abiding members, they do tend to be a little suspicious when dealing with unknown people or situations. They have to be if they want to go home alive. That's not something most of us have to deal with. If you cut them some slack if they are a little gruff at first, you will generally find that they are very understanding once they know that you are not one of their "usual customers".