I see no links between infosec and functional programming.
Big FP shops will have solved this of course. I doubt StanChart or Jane Street are losing any sleep over it.
They are mostly famous in tech circles for one day one of their interns Yaron Minsky saying, hey let's rewrite everything in OCaml. And they did, and were wildly successful, and he's the CTO now. They bet big on FP and it happened to be an excellent fit for their problem domain.