The bottom line is that Starbucks does not want a horse in this race. Their policy is that they prefer customers to not bring guns to their store, but that their store managers and employees are to do nothing about it. They are not to complain to customers, withhold service, scowl, nothing.
And, if those with guns, *or* those who object to guns, become unruly, then they are to call the cops. But only then.
The bottom line is that if you want to take a gun into a Starbucks, fine. But they don’t want you to do so as a “statement”.
Truthfully, I don’t see much wrong in this policy, because it leans towards “no soliciting”. Their business is to sell coffee and coffee-like byproducts, not to be a platform for political arguments.
Except for homo-marriage. They are all-in on that platform.