The problem with your reasoning is that its discriminatory in the parameters you set.
When you set impossible constraints that neglect requirements for sustainability, and tell people to do the impossible, you pigeonhole and sieve only the people you are actually looking for (the ones that can meet that sieve).
The lying, and deceit that you do, naturally occur after-the-fact (which blind people don't notice, often making them evil). The danger of most deceit and lying occur where you say something truthful omitting something important that they know, but then later contradict yourself in the outcome. These are called lies of omission. Deceivers and Vipers take full effect of these actions pretending its not them, its the circumstance, but a circumstance they control.
Of course the middle team would be the only ones left, after all you tortured your senior team having them baby a LLM driving them to burnout, and the junior team lacked the knowledge that makes the difference between Junior and Mid, to be productive. You set a filter that only your midlevel team could meet, and any conclusions you make will equally conform to your initial decisions in the criteria you set which is you don't want to hire young people, or old people. You want them just right, and there are laws against age discrimination. People have tried to get around these laws for years, and have never had more luck in evading these than now; with the advent of blackbox AI which can obscure these type of decisions through hiding them in the weights. Short term, there will of course be more profit, long-term the lawsuits will get you, and your good character which you thought you had will not be good.
Additionally, you have your perfect team left that is wholly dependent on LLM, who won't be able to solve the rare but inevitable problems the senior level people would (before they occur).