I'd like some examples of that because I've never heard of such an absurd thing.
And I've never worked for a small company.
A corporation is usually "owned" by individuals, as stockholders.
That is private property. There is no explicit or implied loss of constitutional rights just because you incorporate your business, your private property.
The corportation maintains and provides a parking lot on their corporate property. That is private property.
The employee probably signed an employment contract, of somekind, stating no guns on the private property.
Oklahoma has a Bill of Rights Article prohibiting the interfernce in the obligations of contracts.
Don't we want our government to protect our property rights and our contracts?
If you did not want guns on your home property and any individual drove into your driveway with a gun in their car or on their hip, as a private property owner, do you not have the right to ask them either remove the guns from your property or themselves from your property?
Of course you do.
On my property, I determine what rights will be exerted.
Their is a stronger constitutional case for the right to bear arms in court room than on private property. A court room is public property.