That's not quite true... the code (essentially) loops over itself infinitely; the only branch is a loop back to the beginning of the program. Since this branch

That's not quite true... the code (essentially) loops over itself infinitely; the only branch is a loop back to the beginning of the program. Since this branch has only one target, it can be a direct jump (as opposed to an indirect one), meaning it would not use the branch trace buffer, and would not cause speculative execution. The author used faulting for branches only to write the program in all mov instructions; if the last 'mov' is replaced with a direct jmp (which, it looks like, can be done with the --no-mov-loop flag to the compiler), no more speculative execution.