What he's saying is that the items at McDonalds are already priced in such a way (simple view is that they're at equilibrium) so that they provide the maximum amount of profit based on the demand curve for a good. The pricing of goods and services is mostly unrelated to the manufacturing costs of those goods.
Now, if it was another business I might be inclined to say that artificially forcing them to raise wages could have adverse consequences. For example: people get fired. But for that to happen the business has to already be operating in such a way where profits are not being completely maximized. This is not the case with McDonalds. Their entire business model revolves around reducing the manufacturing costs of their goods. They treat their employees as poorly as the law will allow them (often worse than that, to be honest). If they had unnecessary personnel, they would have fired them already.
[Rant Incoming]
Perhaps raising labor costs on McDonalds might make some of the franchises go in the red, but who cares? McDonald's is a terrible business and it's hurting all of us. Here are just a few awesome things they do:
Seriously, McDonalds does nothing good. They're bad for the economy, bad for the environment, bad for our political process, bad for the health of our citizens. It's not a good business, and I don't see why people have just come to accept it as an American staple. We've become so focused on low priced inferior quality goods that we don't realize the companies that sell them are destroying our local economies. Meanwhile, big money interests and our lovely media have the middle class and working class at each other's throats talking about, "Single mothers who work in food service don't deserve this and that."
If McDonalds goes away, the local food businesses in the area will come back. They will provide better food and pay their workers better wages.