If it was on something like BTRFS it’d probably be fine, though I imagine there’s still a small window where the FS could flush while the file is being written. renameat2 has the EXCHANGE flag to atomically switch 2 files, so if arch maintainers want to fix it they could do
Write to temporary file
Fsync temporary file
Renameat2 EXCHANGE temporary and target
Fsync directory (optional, since a background flush would still be atomic, just might take some time)