To be honest, I think when I heard them speak, they're kind of saying yes, FreeBSD is awesome but that the main reason is that the early people there liked FreeBSD so they just stuck with it. And that it's a good choice, but they don't claim these are things that would be impossible to do with optimizations in Linux.
Because FreeBSD is known for having the best network stack. The code is elegant and clean. And, at least until a few years ago, it was the preferred choice to build routers or firewalls.
AFAIK, they were the first to implement BPF for production ready code almost 3 decades ago.
