...Um...so we can ask the Magistrates (Heyhey look at that, something for them to do already!) but I'm quite confident that there exists no rule nor spirit of a rule that says one cannot keep an open position open indefinitely and at some point in the future appoint whoever he wishes.
No, seriously, it's probably a supremely bad idea, but idiocy isn't rulebreaking, and if the ruler appoints lordships, then he does in fact have the power to appoint who he wishes when he wishes. Now the placeholder rule, if I understand correctly, is when the ruler doesn't want to leave the position open because that leads to stats penalties and lower taxes, so in order to mitigate this mechanical penalty he appoints someone temporarily to the position with the understanding that the temp will step down once the intended duke can resume his position. Furthermore, that only becomes an issue if in fact the temp does step down and it was due to the predetermined agreement.
You can all split hairs defining it but the fact, I believe, remains clear:
There's nothing wrong with appointing no one to a position.
There's nothing wrong with appointing your friend to the position as long as you...actually, no, screw that and the craven rulers and hypocrites who talk about always requiring IC justification: If you have the power to appoint someone to a position, it's 100% A-OK to appoint some random dude to the position. Your realm might protest, but I don't think it's something that Tom/the Titans/the Magistrates should get their hands into. Obviously IR and SC remain in effect, but if King Random sees that his capital city of Screwed has no duke and decides to label a roulette wheel with all the names of nobles who are eligible for the position then throws a marble on there, and it turns out he appoints Sir Dumbass to Duke Dumbass then there can be a whole ton of intrarealm conflict (Hooray! Because apparently people like that!) but no lightning storms striking down the monumentally whimsical King Random.
Oh, and since I might have strayed from the original point, it's also perfectly fine for King Favoritism to appoint Sir Brownnose as well. So what? Yeah, poor form, but that's why you grab your torches and pitchforks and oust King Favoritism. The king really doesn't need to give a justification, as long as he doesn't do some excessive OOC stuff to make his realm uninviting to newcomers. Hard to imagine King Favoritism not doing that, but sometimes, there really are just the rare exceptions where the player's friend really wants it and real-life friendships bleed into the game. As long as it's not the whole realm, I think, it's just annoying, but not exactly wrong.
As for King Nepotism or King Narcissist, who appoint family members and himself, respectively, well, nothing to do there really. It's completely within his bounds, and thankfully only two characters from the same family can exist on a single continent. You have all council positions and the two largest cities taken by two characters from the same family? Your ruler holds all but one council position and sits as duke of the capital? Ok, if you're discontent do something about it. Can't? Oh well too bad, go somewhere else if it vexes you so much. Eventually if enough people are also annoyed by it the realm will wither and die due to lack of player support.
Anyway, what isn't good is if you try to circumvent game mechanics by appointing a temp whom you replace shortly thereafter according to your plan...whose intention was to circumvent game mechanics.
