So they know that the scumbag is killing his own citizens, but can't do anything for... reasons...
And they HAVE TO make him king if he saves the princess... just because?...
It's like this comic has one foot in maturity (penis tentacle), and the other in silly childishness, tonally anyway. And yes I know there are "plot reasons" they have to do these things, but it doesn't change the fact they're silly.
But I'm enjoying the childish sillyness all the same.
Powerful people can get away with things because they have influence over the system, and when they can cause more damage if they are not left alone.
Like hypothetically, if superman or homelander or omniman or whoever decided they wanted to do crimes, they couldn't have anything done to them because of the consequences that would occur. Attempting to bring them to justice would have significant casualties to say the slightest.
You can either let them get away with murder of dozens of people and look the other way, or you can have thousands, tens of thousands of casualties in the war to take them down and hold them accountable.
If you want a IRL example just look at people like Putin who literally poisons his opposition with neurotoxin and jails them, and gets away with it.
Or there is the rule of law, where even though it is well known that crimes are occurring, if no direct evidence is brought forth they cannot be charged. Aka Al Capone, who only was brought down via tax crimes.
Monarchies are dumb enough typically, it's not any worse that someone who achieves the great feat of conquering the Tower and saving the princess would become king. At least that is a merit based accomplishment. In systems of government like this, might is often right.
I am not saying this isn't childish(I have no opinion), but it's kinda childish to just label everything childish/lazy/bad writing when real life has tons of examples of situations like this. Childish to just assume that the a powerful person (both politically and physically) can just be brought down because they are ethically bad people. Childish to assume that all forms of government value and protect individual and human rights(it may not even be legally wrong in this government for that guy to treat his subjects as he pleases).