This trend started in great earnest with the discussion of smoking bans on business property. Governments at all levels are increasingly saying that business owners cannot set policy on their property, because even though private property, they are places of public accommodation.
So, it certainly does follow that the Indiana legislature approved a law permitting employees to bring guns onto business property, regardless of whether the business owner approves. From the Indy Star:
The Star got it right on business as loser here. I'm all for the right to self-defense and the right to bear arms. However, the rights or property come first for me. If I don't want your gun on my property, that should be my call. Alas, in today's America, if you own business property, you can go to hell. Someone else gets primacy on what is now only nominally 'your land'.
Business groups argue that companies should be able to set their own policies on handguns to safeguard their property and employees. They point to workplace incidents where disgruntled employees have retrieved a weapon from their cars and opened fire.