I think there might be a terminology mixup here but he probably meant zero-overhead abstraction. And in any case, the point he's making is not a strawman argument.
He talked about more than just unique_ptr if you actually watch the video, but I don't even get why you're dying to have such a pointless argument here. When you see free lunches offered somewhere, do you start arguing with people how everyone is wrong and there is such a thing as a free lunch too? Is it so hard to actually take the point and just move on instead of dissecting it like a mathematical theorem?
Premise one: C++ has zero overhead for most of its features, like smarts pointers: if you don't use them, they cost nothing.
Premise two: using features like smart pointers adds a cost to your C++ program.
Conclusion (due to the strawman logical fallacy): C++ is not zero overhead because there exists a feature that has a cost if you use it.
I'd like to see the reasoning that leads to the same conclusion without resorting to the strawman logical fallacy.