It's not a matter of scale. It's a matter of being publicly traded. Yes, those people investing in that corporation are indeed private individuals. They don't (normally) get a vote on any policy or direction the company is thinking about going, you know that right? Their rights do not transfer to the corporation, because the corporation is it's own person. This is similar to the way you cannot transfer your rights to another person; say... you cannot give YOUR right to vote to someone who does not have that right.
When the founding fathers wrote the constitution, they did not envision a world run by large, public corporations. Even the largest companies of their day were run by an individual or a person, and that person was responsible for the company. How is it not just painfully obvious that it is wrong for a company to be responsible for itself? How do you punish a company for wrong doing? You can't jail it. You can't execute it. It can't do community service. It feels no shame, no remorse, and no hope for a better job next time.
Corporate person is wrong, plain and simple.
If it were a mom and pop store, I'm sure this wouldn't be an issue. If it was, no, I wouldn't shop there. I do all I can to preserve those stores, normally, including driving eight miles out of my way to go to a locally owned "mom and pop drug shop" to get my son's prescriptions filled.
As for the guns being banned in public buildings thing? Maybe where you live. In Texas it is legal (as long as you have a permit to carry) to carry a concealed weapon into the capitol building in Austin, or any other gov't building in the state. Some of the bigger cities have city ordinances that prohibit carrying into a city hall meeting or something of that nature, but you can still carry in the building.
OFF-TOPIC, sorry.
Corporate person hood is wrong, therefore, Walgreen's should not have been allowed to fire that employee for exercising one of his constitutionally protected rights.