Linus has said a lot of stuff over the years and not all of it was on the money. Still, he did a lot of good and I'm very grateful for it, Linux has been my daily driver for almost two decades now (basically from when I stopped using SGI because there was no point any more).
But bugs in large codebases will always be a thing, and even though the eyes looking at FreeBSD are very, very good eyes, indeed there are not enough of them. The more interesting thing here is that they picked a really hard target. If they had done the same with Linux I would expect the number of bugs to be quite a bit higher.