Panics aren't exceptions, any "panic" in Rust can be thought of as an abort of the process (Rust binaries have the explicit option to implement panics as aborts). Companies like Dropbox do exactly this in their similar Rust-based systems, so it wouldn't surprise me if Cloudflare does the same.

"Banning exceptions" wouldn't have done anything here, what you're looking for is "banning partial functions" (in the Haskell sense).