I don't know about you but a 3x performance increase going from a scripting language with fast iteration times to a programming language that has long compilation times plus a borrow checker is hardly worth the risk of a rewrite to the average company.
Add on top the fact that one of the performance problems was interfacing nginx with luajit, aka there are two unnecessary memory copies.
When I think about these things, I'm thinking cloudflare was lucky enough to outgrow lua rather than being lucky to have gotten away with luajit.
They got lucky, choosing a niche language and a massive amount of tech debt as their primary technology stack.
But in the end, Cloudflare is one company. Who gives a what they did?