I assume you have no problem with muslims who have the same attitude toward Christians and Jews...........or do you consider that wrong because of the 1st Amendment?
It has nothing to do with the 1a. First, Islam is a cult. It is not a religion. Therefore the 1a does not apply. Second, doing business with Muslims is a matter of free will. It has nothing to do with the US Constitution. As for owning a business, that is a property right that has been unjustly imposed upon by consent of our government on many fronts. Property is something that I will fight for, whether it is my business or house. When anyone that de-values my property I will consider them as a direct infringement of my freedom and liberty. Our government exists to protect our freedom and liberty, although that has long been lost. That is the reason why we need to take things in our own hands.