That's exactly his point. You don't hear the apostrophe but you do hear the "s," meaning that Thomas and Thomas' cannot be distinguished. And so Thomas's must be used instead.
American Heritage is much better. They respond to usage, but much more conservatively. And their entries will actually have brief explanations from their "usage panel" about ambiguous or changing meanings.
Corporate personhood includes the ability for corporations to own property, enter contracts, and serve as plaintiff or defendant.
And corporations have civil rights only as a tool of shareholders' civil rights. For example, Citizens United was a corporation formed expressly for the purposes of political speech.
I am very thankful for tipping in the US. It provides an incentive for better service, allows me to express my gratitude to waitstaff directly, and gives me influence over the pricing that I do not have in any other kind of transaction. It's great!