But a "fix" in libc wouldn't help for the security risk because an attacker could still emit the system call directly.
(Unless I misunderstood what the fix would be)
Otoh if you want libc to be possibly a little too clever, perhaps it could make an effort to try to discover a sensible value for argv[0] based on looking around /proc etc to find the path to the binary. That seems like way too much complexity and failure points for a few mostly inconsequential corner cases.