Removing the whitelist for Captain would be positively god awful. You think it's bad now, but I guarantee you it would be worse without it. Are there problems? Certainly, but removing the whitelist is not only a drastic move, it's counter-intuitive. The story section might be a sham, but there is a reason we vote our candidates in at all.
On the synthetic side, this can be solved mechanically. Simply remove or gimp their ability to deal damage. Make it so that they cannot strike without being struck first.
Predators are trickier because they're an active antagonistic force. Since I don't pay much attention to them I can only advocate that they also be fixed mechanically, with some kind of meta-hunting system where they mark individuals who can either accept or deny hunting status, locking them into a duel.