@Lawbin
well as you read by the spoiler he got the position of emperor by betraying the real emperor in the secret realm who was the ancestor of the fml , so we can expect that he is very paranoid about a lot of things, so trying to cut a problem from the root is a very reasonable option, the fml part was just a desert since she was from the same lineage and in this type of novels as well "pedigree" is a very important thing so bringing her to his family could not only increase the crown prince pedigree but overall control of every faction so i could not call him really stupid because his choice to meddle with them is very reasonable even more when we put the seer guy who can read destiny and everyone knows that he read both of them destiny but is keeping them a "secret" and this only means problem for the current ruler of course so let's be logical, if both of them are not going to cause him problem why would he hidden? the only reasonable guess is that both of them are going to cause him problem or middle with the seer own life as well (as causing problem to him) but if this was the reality, the seer could ask the emperor for help ,something he did not do so the only option left is problem to the emperor himself!
the main beef i have with it and the only downside is about the methods he used, he gave too little credit to them after all they have not truthfully showed their potential for the world yet as i stated in the spoiler as well, so overall i believe is a good balance because with his current level against the mc and so on, if he did not make one or two mistakes is impossible for the mc's win at this stage and so the novel would end, so overall was a good writing in my opinion since it have reasonable cause-effect; the resolution is direct linked with the novel overall plot structure (concubines-crown princes-emperor degrees and so on) and have a very obvious flaw that the mc can take advantage off but that would not slap on your face as asspull! since not taking them serious enough because their own levels are so far apart is also a reasonable thing to do, he send one of his best expert that was the strongest guy on the entire city to make sure everything would work well.
the main downside of his control as that he did not really studied the fml enough since she was already the pedigree, and by what we know about his caution in future chapters and everything else, he should have been keeping a eye on her and her family something that he failed to do so, maybe because no one knows that he really killed the previous emperor!.