The CPU doesn't know what processes are, that's handled by the OS. So there still needs to be a fault.
In effect: we don't know how secure it was...
But if it was good and Intel removed it then why Intel keeps so many useless crap in ?? Good parts - remove, bad - needed for backward compatibility... Can, finally, someone tell backward compatibility with WHAT ? DOS 4.0 ? Drivers for pre-winonly modems using plain ISA or PCI slots ??
Or maybe just like with EVE Online code (few years ago?) - no one anymore knows how some parts works...